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Abstract:

Provided are a light-emitting device and a photovoltaic cell having
excellent characteristics. A light-emitting device (10) includes a
cathode (34), an anode (32), a light-emitting layer (50) interposed
between the cathode (34) and the anode (32), and an electron injection
layer (44) provided between the cathode (34) and the light-emitting layer
(50) and connected to the cathode (34), in which at least one of the
anode (32) and the cathode (34) contains a conductive material having an
aspect ratio of 1.5 or more, and the electron injection layer (44)
contains an organic compound having at least one of an ionic group and a
polar group.

Claims:

1. A light-emitting device comprising: a cathode, an anode, a
light-emitting layer interposed between the cathode and the anode, and an
electron injection layer provided between the cathode and the
light-emitting layer and connected to the cathode, wherein at least one
of the cathode and the anode comprises a conductive material having an
aspect ratio of 1.5 or more, and the electron injection layer comprises
an organic compound having at least one of an ionic group and a polar
group.

2. The light-emitting device according to claim 1, wherein the
light-emitting device further comprises a substrate, and the cathode, the
electron injection layer, the light-emitting layer and the anode are
stacked on the substrate in this order such that the cathode is closer to
the substrate.

3. The light-emitting device according to claim 1, wherein the cathode
has optical transparency.

4. The light-emitting device according to claim 1, wherein the conductive
material contains a material selected from the group consisting of a
metal, a metal oxide, a carbon material, and combinations thereof.

5. The light-emitting device according to claim 1, wherein the ionic
group is at least one group selected from the group consisting of: a
group represented by formula: --SM, a group represented by formula:
--C(═O)SM, a group represented by formula: --CS2M, a group
represented by formula: --OM, a group represented by formula:
--CO2M, a group represented by formula: --NM2, a group
represented by formula: --NRM, a group represented by formula:
--PO3M, a group represented by formula: --OP(═O)(OM)2, a
group represented by formula: --P(═O)(OM)2, a group represented
by formula: --C(═O)NM2, a group represented by formula:
--C(═O)NRM, a group represented by formula: --C(═S)NRM, a group
represented by formula: --C(═S)NM2, a group represented by
formula: --B(OM)2, a group represented by formula: --BR3M, a
group represented by formula: --B(OR)3M, a group represented by
formula: --SO3M, a group represented by formula: --SO2M, a
group represented by formula: --NRC(═O)OM, a group represented by
formula: --NRC(═O)SM, a group represented by formula:
--NRC(═S)OM, a group represented by formula: --NRC(═S)SM, a group
represented by formula: --OC(═OO)NM2, a group represented by
formula: --OC(═O)NRM, a group represented by formula:
--OC(═S)NM2, a group represented by formula: --OC(═S)NRM, a
group represented by formula: --SC(═OO)NM2, a group represented
by formula: --SC(═O)NRM, a group represented by formula:
--SC(═S)NM2, a group represented by formula: --SC(═S)NRM, a
group represented by formula: --NRC(═O)NM2, a group represented
by formula: --NRC(═O)NRM, a group represented by formula:
--NRC(═S)NM2, a group represented by formula: --NRC(═S)NRM,
a group represented by formula: --NR3M', a group represented by
formula: --PR3M', a group represented by formula: --OR2M', a
group represented by formula: --SR2M', a group represented by
formula: --IRM', a group represented by eliminating a hydrogen atom from
an aromatic ring selected from aromatic compounds represented by
following formula (n-1) to formula (n-13), wherein R represents a
hydrogen atom or a hydrocarbyl group optionally having a substituent, M
represents a metal cation or an ammonium cation that may have a
substituent, and M' represents an anion: ##STR00059## ##STR00060##

6. The light-emitting device according to claim 1, wherein the polar
group is at least one group selected from the group consisting of a
carboxy group, a sulfo group, a hydroxy group, a mercapto group, an amino
group, a hydrocarbylamino group, a cyano group, a pyrrolidonyl group, a
monovalent heterocyclic group and a group represented by following
formula (I) to formula (IX): --O--(R'O)m--R'' (I) ##STR00061##
--S--(R'S)q--R'' (III) --C(═O)--(R'--C(═O))q--R''
(IV) --C(═S)--(R'--C(═S))q--R'' (V)
--N{(R')qR''}2 (VI) --C(═O)O--(R'--C(═O)O)q--R''
(VII) --C(═O)--O--(R'O)q--R'' (VIII)
--NHC(═O)--(R''NHC(═O))q--R'' (IX) wherein, in formula (I)
to formula (IX), R' represents a hydrocarbylene group optionally having a
substituent, R'' represents a hydrogen atom, a hydrocarbyl group
optionally having a substituent, a carboxy group, a sulfo group, a
hydroxy group, a mercapto group, an amino group, a group represented by
formula: --NRc2, a cyano group, or a group represented by
formula: --C(═O)NRc2, R''' represents a trivalent
hydrocarbon group optionally having a substituent, m represents an
integer of 1 or more, q represents an integer of zero or more, Rc
represents an alkyl group having 1 to 30 carbon atoms that may have a
substituent, or an aryl group having 6 to 50 carbon atoms that may have a
substituent, and when R', R'', and R''' are each plurally present, each
R', R'', and R''' may be the same as or different from each other.

7. The light-emitting device according to claim 1, wherein the organic
compound having at least one of an ionic group and a polar group is a
conjugated compound.

8. The light-emitting device according to claim 7, wherein the conjugated
compound has a structural unit represented by following formula (X):
##STR00062## wherein, in formula (X), Ar1 represents an aromatic
group having a valence of (n1+1); R1 represents a direct bond
or a group having a valence of (m1+1); X1 represents a group
having an ionic group or a polar group; m1 and n1 are each
independently an integer of 1 or more; when R1 is a direct bond,
m1 is 1; when R1, X1 and m1 are each plurally
present, each R1, X1, and m1 may be the same as or
different from each other, or a structural unit represented by following
formula (XI): ##STR00063## wherein, in formula (XI), Ar2
represents an aromatic group having a valence of (n2+2); R2
represents a direct bond or a group having a valence of (m2+1);
X2 represents a group having an ionic group or a polar group;
m2 and n2 are each independently an integer of 1 or more; when
R2 is a direct bond, m2 is 1; when R2, X2 and m2
are each plurally present, each R2, X2 and m2 may be the
same as or different from each other, or both of structural units
represented by formula (X) and formula (XI).

9. The light-emitting device according to claim 8, wherein Ar1
represents a group optionally having a substituent and represented by
eliminating (n1+1) hydrogen atoms from an aromatic ring of aromatic
compounds represented by any one of the following formulae; and Ar2
represents a group optionally having a substituent and represented by
eliminating (n2+2) hydrogen atoms from an aromatic ring of aromatic
compounds represented by any one of the following formulae. ##STR00064##

10. The light-emitting device according to claim 1, wherein at least one
of the cathode, the anode, and the electron injection layer contains an
ionic compound.

11. The light-emitting device according to claim 10, wherein the ionic
compound is a compound having a structure represented by following
formula (h-1): Mm'aX'n'-.sub.b (h-1) wherein, in formula
(h-1), Mm'.sup.+ represents a metal cation; X'n'- represents an
anion; a and b are each independently an integer of 1 or more; when
Mm'.sup.+ and X'n'- are each plurally present, each
Mm'.sup.+ and X'n'- may be the same as or different from each
other.

12. The light-emitting device according to claim 10, wherein the electron
injection layer comprises the ionic compound, and the ratio of the ionic
compound in the electron injection layer is 0.1 parts by weight or more
and 100 parts by weight or less, with respect to 100 parts by weight of
the organic compound having at least one of an ionic group and polar
group.

13. A method for manufacturing a light-emitting device comprising a
cathode, an anode, a light-emitting layer interposed between the cathode
and the anode, and an electron injection layer provided between the
cathode and the light-emitting layer and connected to the cathode, the
method comprising the steps of: applying a coating solution that
comprises a conductive material having an aspect ratio of 1.5 or more,
thereby forming at least one of the cathode and the anode; and applying a
coating solution that comprises an organic compound having at least one
of an ionic group and a polar group, thereby forming the electron
injection layer connected to the cathode.

14. A photovoltaic cell comprising: a cathode, an anode, a charge
separating layer interposed between the cathode and the anode, and an
electron injection layer provided between the cathode and the charge
separating layer and connected to the cathode, wherein at least one of
the cathode and the anode comprises a conductive material having an
aspect ratio of 1.5 or more, and the electron injection layer comprises
an organic compound having at least one of an ionic group and a polar
group.

15. A method for manufacturing a photovoltaic cell comprising a cathode,
an anode, a charge separating layer interposed between the cathode and
the anode, and an electron injection layer provided between the cathode
and the charge separating layer and connected to the cathode, the method
comprising the steps of: applying a coating solution that comprises an
organic compound having at least one of an ionic group and a polar group,
thereby forming the electron injection layer connected to the cathode,
and applying a coating solution that comprises the conductive material
having the aspect ratio of 1.5 or more, thereby forming at least one of
the cathode and the anode.

Description:

TECHNICAL FIELD

[0001] The present invention relates to a light-emitting device and a
photovoltaic cell, and a method for manufacturing the same.

BACKGROUND ART

[0002] For improving light emitting efficiency and photovoltaic efficiency
in an electronic device such as a light-emitting device containing
organic compounds as materials for a light-emitting layer and a
photovoltaic cell containing organic compounds as materials for a charge
separating layer, an electron injection characteristic is required to be
improved in such electronic device.

[0003] To improve the electron injection characteristic, (1) a method for
forming a cathode by depositing a metal layer having a small work
function further on a metal layer having a large work function such as
aluminum using a deposition method; (2) a method for forming a cathode by
depositing an alloy layer in which the alloy is made of a metal having a
large work function and a metal having a small work function using a
deposition method; and (3) a method for forming an electron injection
layer made of a material such as an alkali metal compound and an alkali
earth metal compound stacked by a deposition method on a cathode made of
a metal layer formed by a deposition method are known.

[0004] When a deposition method is used for forming a metal layer or an
alloy layer, a batch process based on a vacuum system is required. As a
result, problems of reduction in yield caused by losing continuity of the
manufacturing process and increase in manufacturing cost arise.

[0005] To solve these problems, a light-emitting device in which an
electron injection layer, a cathode, and the like are formed by a coating
method that forms a coating film using a coating solution has been
reported (Patent Document 1 and Non Patent Document 1).

RELATED ART DOCUMENTS

Patent Document

[0006] Patent Document 1: WO 2007/009331

Non Patent Document

[0006]

[0007] Non Patent Document 1: Advanced Materials 2007, 19, 810

DISCLOSURE OF INVENTION

Problem to be Solved by the Invention

[0008] However, when higher electric conductivity of electrodes including
an anode and a cathode is tried to be achieved, thicknesses of the
electrodes are required to be thick. This may cause deterioration of
transparency of emitting light because electrode transparency is reduced,
and as a result, brightness of the light-emitting device may be
deteriorated. Therefore, when the thickness of the electrode becomes
thick, it is difficult to form a light-emitting device that emits light
from a side of electrode having a thick thickness. In addition, when the
thickness of the electrode becomes thick, manufacturing cost may become
high because the amount of used materials is increased.

[0009] The present invention aims to provide a light-emitting device that
has excellent electric conductivity even in the case of thin thickness of
electrode, has an improved electron injection characteristic from the
cathode, and further has excellent light-emitting brightness and a method
for manufacturing the same that can improve productivity, and a
photovoltaic cell that has excellent electric conductivity even in the
case of thin thickness of the electrode, has an improved electron
injection characteristic to the cathode, and further has excellent
photovoltaic efficiency and a method for manufacturing the same that can
improve productivity.

Means for Solving Problem

[0010] The inventors of the present invention have eagerly investigated
and have accomplished the present invention. According to the present
invention, following [1] to [15] are provided:

[1] A light-emitting device comprising:

[0011] a cathode, an anode, a
light-emitting layer interposed between the cathode and the anode, and an
electron injection layer provided between the cathode and the
light-emitting layer and connected to the cathode, wherein

[0012] at
least one of the cathode and the anode comprises a conductive material
having an aspect ratio of 1.5 or more, and

[0013] the electron injection
layer comprises an organic compound having at least one of an ionic group
and a polar group. [2] The light-emitting device according to above [1],
wherein the light-emitting device further comprises a substrate, and the
cathode, the electron injection layer, the light-emitting layer and the
anode are stacked on the substrate in this order such that the cathode is
closer to the substrate. [3] The light-emitting device according to above
[1] or [2], wherein the cathode has optical transparency. [4] The
light-emitting device according to any one of above [1] to [3], wherein
the conductive material contains a material selected from the group
consisting of a metal, a metal oxide, a carbon material, and combinations
thereof. [5] The light-emitting device according to any one of above [1]
to [4], wherein the ionic group is at least one group selected from the
group consisting of:

[0014] a group represented by formula: --SM, a group
represented by formula: --C(═O)SM, a group represented by formula:
--CS2M, a group represented by formula: --OM, a group represented by
formula: --CO2M, a group represented by formula: --NM2, a group
represented by formula: --NRM, a group represented by formula:
--PO3M, a group represented by formula: --OP(═O)(OM)2, a
group represented by formula: --P(═O)(OM)2, a group represented
by formula: --C(═O)NM2, a group represented by formula:
--C(═O)NRM, a group represented by formula: --C(═S)NRM, a group
represented by formula: --C(═S)NM2, a group represented by
formula: --B(OM)2, a group represented by formula: --BR3M, a
group represented by formula: --B(OR)3M, a group represented by
formula: --SO2M, a group represented by formula: --SO2M, a
group represented by formula: --NRC(═O)OM, a group represented by
formula: --NRC(═O)SM, a group represented by formula:
--NRC(═S)OM, a group represented by formula: --NRC(═S)SM, a group
represented by formula: --OC(═O)NM2, a group represented by
formula: --OC(═O)NRM, a group represented by formula:
--OC(═S)NM2, a group represented by formula: --OC(═S)NRM, a
group represented by formula: --SC(═O)NM2, a group represented
by formula: --SC(═O)NRM, a group represented by formula:
--SC(═S)NM2, a group represented by formula: --SC(═S)NRM, a
group represented by formula: --NRC(═O)NM2, a group represented
by formula: --NRC(═O)NRM, a group represented by formula:
--NRC(═S)NM2, a group represented by formula: --NRC(═S)NRM,
a group represented by formula: --NR3M', a group represented by
formula: --PR3M', a group represented by formula: --OR2M', a
group represented by formula: --SR2M', a group represented by
formula: --IRM', a group represented by eliminating a hydrogen atom from
an aromatic ring selected from aromatic compounds represented by
following formula (n-1) to formula (n-13), wherein R represents a
hydrogen atom or a hydrocarbyl group optionally having a substituent, M
represents a metal cation or an ammonium cation that may have a
substituent, and M' represents an anion:

##STR00001## ##STR00002##

[0014] [6] The light-emitting device according to above [1] to [5],
wherein the polar group is at least one group selected from the group
consisting of a carboxy group, a sulfo group, a hydroxy group, a mercapto
group, an amino group, a hydrocarbylamino group, a cyano group, a
pyrrolidonyl group, a monovalent heterocyclic group and a group
represented by following formula (I) to formula (IX):

--O--(R'O)m--R'' (I)

##STR00003## --S--(R'S)q--R'' (III)

--C(═O)--(R'--C(═O))q--R'' (IV)

--C(═S)--(R'--C(═S))q--R'' (V)

--N{(R')qR''}2 (VI)

--C(═O)O--(R'--C(═O)O)q--R'' (VII)

--C(═O)--O--(R'O)q--R'' (VIII)

--NHC(═O)--(R'NHC(═O))q--R'' (IX)

wherein, in formula (I) to formula (IX),

[0015] R' represents a
hydrocarbylene group optionally having a substituent,

[0016] R''
represents a hydrogen atom, a hydrocarbyl group optionally having a
substituent, a carboxy group, a sulfo group, a hydroxy group, a mercapto
group, an amino group, a group represented by formula: --NRc2,
a cyano group, or a group represented by formula:
--C(═O)NRc2,

[0017] R''' represents a trivalent hydrocarbon
group optionally having a substituent,

[0018] m represents an integer of
1 or more,

[0019] q represents an integer of zero or more,

[0020] Rc
represents an alkyl group having 1 to 30 carbon atoms that may have a
substituent, or an aryl group having 6 to 50 carbon atoms that may have a
substituent, and

[0021] when R', R'', and R''' are each plurally present,
each R', R'', and R''' may be the same as or different from each other.
[7] The light-emitting device according to any one of above [1] to [6],
wherein the organic compound having at least one of an ionic group and a
polar group is a conjugated compound. [8] The light-emitting device
according to above [7], wherein the conjugated compound has a structural
unit represented by following formula (X):

##STR00004##

[0021] wherein, in formula (X), Ar1 represents an aromatic group
having a valence of (n1+1); R1 represents a direct bond or a
group having a valence of (m1+1); X1 represents a group having
an ionic group or a polar group; m1 and n1 are each
independently an integer of 1 or more; when R1 is a direct bond,
m2 is 1; when R1, X1 and m1 are each plural, each
R1, X1, and m1 may be the same as or different from each
other,

[0022] or a structural unit represented by following formula
(XI):

##STR00005##

[0022] wherein, in formula (XI), Ar2 represents an aromatic group
having a valence of (n2+2); R2 represents a direct bond or a
group having a valence of (m2+1); X2 represents a group having
an ionic group or a polar group; m2 and n2 are each
independently an integer of 1 or more; when R2 is a direct bond,
m2 is 1; when R2, X2 and m2 are each plural, each
R2, X2 and m2 may be the same as or different from each
other,

[0023] or both of structural units represented by formula (X)
and formula (XI). [9] The light-emitting device according to above [8],
wherein Ar1 represents a group optionally having a substituent and
represented by eliminating (n1+1) hydrogen atoms from an aromatic
ring of aromatic compounds represented by any one of the following
formulae; and Are represents a group optionally having a substituent and
represented by eliminating (n2+2) hydrogen atoms from an aromatic
ring of aromatic compounds represented by any one of the following
formulae.

##STR00006##

[0023] [10] The light-emitting device according to any one of above [1]
to [9], wherein at least one of the cathode, the anode, and the electron
injection layer contains an ionic compound. [11] The light-emitting
device according to above [10], wherein the ionic compound is a compound
having a structure represented by following formula (h-1):

Mm'.sup.+aX'n'-b (h-1)

wherein, in formula (h-1), Mm'.sup.+ represents a metal cation;
represents an anion; a and b are each independently an integer of 1 or
more; when Mm'.sup.+ and are each plurally present, each
Mm'.sup.+ and may be the same as or different from each other. [12]
The light-emitting device according to above [10] or [11], wherein the
electron injection layer contains the ionic compound, and the ratio of
the ionic compound in the electron injection layer is 0.1 parts by weight
or more and 100 parts by weight or less, with respect to 100 parts by
weight of the organic compound having at least one of an ionic group and
polar group. [13] A method for manufacturing a light-emitting device
according to any one of above [1] to [12] comprising a cathode, an anode,
a light-emitting layer interposed between the cathode and the anode, and
an electron injection layer provided between the cathode and the
light-emitting layer and connected to the cathode, the method comprising
the steps of:

[0024] applying a coating solution that comprises a
conductive material having an aspect ratio of 1.5 or more, thereby
forming at least one of the cathode and the anode, and

[0025] applying a
coating solution that comprises an organic compound having at least one
of an ionic group and a polar group, thereby forming the electron
injection layer connected to the cathode. [14] A photovoltaic cell
comprising:

[0026] a cathode, an anode, a charge separating layer
interposed between the cathode and the anode, and an electron injection
layer provided between the cathode and the charge separating layer and
connected to the cathode, wherein

[0027] at least one of the cathode and
the anode comprises a conductive material having an aspect ratio of 1.5
or more, and

[0028] the electron injection layer comprises an organic
compound having at least one of an ionic group and a polar group. [15] A
method for manufacturing a photovoltaic cell comprising a cathode, an
anode, a charge separating layer interposed between the cathode and the
anode, and an electron injection layer provided between the cathode and
the charge separating layer and connected to the cathode, the method
comprising the steps of:

[0029] applying a coating solution that contains
an organic compound having at least one of an ionic group and a polar
group, thereby forming the electron injection layer connected to the
cathode, and

[0030] applying a coating solution that contains the
conductive material having the aspect ratio of 1.5 or more, thereby
forming at least one of the cathode and the anode.

EFFECT OF THE INVENTION

[0031] A light-emitting device and a photovoltaic cell of the present
invention comprise electrodes made by using a material that can reduce an
electrode thickness while improving electric conductivity and an electron
injection layer made by using a material that has an excellent electron
injection characteristic. Therefore, with the light-emitting device and
the photovoltaic cell of the present invention, light transparency can be
improved because of the improvement of transparency of the electrodes and
further the electron injection characteristic of the electron injection
layer can be improved. As a result, the light-emitting brightness of the
light-emitting device and the photovoltaic efficiency of the photovoltaic
cell can be improved.

[0032] With the method for manufacturing a light-emitting device and a
photovoltaic cell of the present invention, the formation step of the
cathode and the following formation step of a charge injection layer are
performed as a convenient coating method that can be performed at normal
pressure (atmospheric pressure). Therefore, the light-emitting device and
the photovoltaic cell having excellent characteristics can be
manufactured in convenient steps with high productivity because the
formation step of the electron injection layer and the formation step of
the cathode can be continuously performed at normal pressure. In
addition, the manufacturing cost can be reduced because the amount of the
used material can be reduced by reduction in the electrode thickness.

BRIEF DESCRIPTION OF DRAWINGS

[0033]FIG. 1 is a cross-sectional view schematically illustrating an
example of constitution of a light-emitting device.

[0036] Hereinafter, embodiments of the present invention will be described
with reference to the drawings. Each drawing only schematically
illustrates shapes, sizes, and arrangements of constituents in such a
degree that the present invention can be understood. The present
invention is not limited by the following description, and each
constituent can be modified within a range without departing from the
scope of the present invention. In each drawing used for the following
description, the same reference numerals may be assigned to the same
constituents and overlapped description may be omitted. Elements of the
present invention are not always manufactured or used in the arrangement
illustrated in the drawings. Hereinafter, one direction of the thickness
direction of the substrate may be described as "upper" and the other
direction of the thickness direction of the substrate may be described as
"lower".

[0037] <Constitution Example of Light-Emitting Device>

[0038] With reference to FIG. 1, an example of constitution of a
light-emitting device will be described.

[0039] A light-emitting device according to an embodiment of the present
invention comprises: a cathode, an anode, a light-emitting layer
interposed between the cathode and the anode, and an electron injection
layer provided between the cathode and the light-emitting layer and
connected to the cathode, in which at least one of the cathode and the
anode contains a conductive material having an aspect ratio of 1.5 or
more, and the electron injection layer contains an organic compound
having at least one of an ionic group and a polar group.

[0040]FIG. 1 is a cross-sectional view schematically illustrating an
example of constitution of a light-emitting device.

[0041] As illustrated in FIG. 1, a light-emitting device 10 comprises an
anode 32 and a cathode 34 as basic constituents, and a layered structure
body 60 interposed between the anode 32 and the cathode 34.

[0042] The layered structure body 60 is constituted by stacking a
plurality of organic layers. At least one layer of the organic layers is
a light-emitting layer 50. The layered structure body 60 also has an
electron injection layer 44 as at least one organic layer of the organic
layers. The electron injection layer 44 is provided between the cathode
34 and the light-emitting layer 50.

[0043] Although the layered structure body 60 can be constituted by only
the organic layers, the layered structure body 60 may further comprise
inorganic layers made of inorganic materials or layers made by mixing an
organic material and an inorganic material.

[0044] In this embodiment, the anode 32 is provided on one of the two main
surfaces facing each other in a direction of the thickness of a first
substrate 22. A hole injection layer 42a is provided so as to be
connected to the anode 32.

[0045] A hole transport layer 42b is provided so as to be connected to the
hole injection layer 42a. The light-emitting layer 50 is provided so as
to be connected to the hole transport layer 42b. The electron injection
layer 44 is provided so as to be connected to the light-emitting layer
50. The cathode 34 is provided so as to be connected to the electron
injection layer 44. A second substrate 24 is provided so as to be
connected to the cathode 34.

[0046] The layered body 60 is stacked on the anode 32. In this
constitution example, the layered structure body 60 is composed of the
hole injection layer 42a, the hole transport layer 42b, the
light-emitting layer 50, and the electron injection layer 44, and is
composed of the organic layers that are interposed between the anode 32
and the cathode 34.

[0047] The light-emitting device 10 is characterized in that at least one
of the cathode 34 and the anode 32 contains a conductive material having
an aspect ratio of 1.5 or more, and the electron injection layer 44
contains an organic compound having at least one of an ionic group and a
polar group.

[0048] Hereinafter, the constituents of the light-emitting device 10 will
be specifically described.

[0049] --Substrate--

[0050] Each of substrates 20 constituting the light-emitting device 10
(the first substrate 22 and the second substrate 24) can be provided so
as to be connected to one of the anode 32 and the cathode 34. The
substrates 20 may be constituted by a material that is not chemically
changed during formation of other layers such as the electron injection
layer and the light-emitting layer. Examples of the material for the
substrates 20 may include glasses, plastics such as polyethylene
terephthalate, polyethylene, polypropylene, and polycarbonate, and
silicon.

[0051] --Cathode--

[0052] In the light-emitting device 10, a material for the cathode 34 is
preferably a material capable of being applied onto the substrates 20 by
a coating method using a coating solution, and the material for the
cathode 34 preferably contains a conductive material having an aspect
ratio of 1.5 or more.

[0053] Examples of the conductive material may include a material
containing one or more materials selected from the group consisting of a
metal, a metal oxide, and a carbon material. Examples of the conductive
materials may include a metal such as aluminum, gold, platinum, silver,
and copper and an alloy thereof; a metal oxide comprising indium oxide,
zinc oxide, tin oxide and mixtures thereof such as indium-tin oxide
(ITO), aluminum-zinc oxide (AZO), indium-zinc oxide (IZO), tin-antimony
oxide and NESA; and a carbon material such as carbon nanotube and
graphite. These conductive materials can be used singly or in combination
of two or more materials.

[0054] Transition metals are preferable as the metal because of their
excellent stability as metals. Metals of group 11 in the periodic table
are more preferable and silver is further preferable. These metals can be
used singly or in combination of two or more metals.

[0055] ITO and IZO are preferable as the metal oxides.

[0056] As the carbon materials, carbon nanotube and graphite are more
preferable, and carbon nanotube is further preferable.

[0057] An aspect ratio refers to a ratio of the longest diameter and the
shortest diameter (longest diameter/shortest diameter) in a rod-like
body, wire-like body, and the like. When an aspect ratio has a
distribution, the aspect ratio refers to the average value. Here, the
average value refers to an arithmetic average value. An aspect ratio of
the conductive material can be determined with reference to a photograph
taken by using a scanning electron microscope.

[0058] The aspect ratio is preferably 2 or more, more preferably 5 or
more, further preferably 10 or more, particularly preferably 50 or more,
especially preferably 100 or more, and extremely preferably 300 or more
because electric conductivity of the cathode is improved.

[0059] When the aspect ratio is less than 1.5, formation of electric
conduction paths may be insufficient. This may cause reduction in
electric conductivity.

[0060] The upper limit of the aspect ratio is not limited. The aspect
ratio is preferably 107 or less, more preferably 106 or less,
further preferably 105 or less, particularly preferably 104,
and especially preferably 103 or less because dispersibility is
improved.

[0061] The conductive material having the aspect ratio of 1.5 or more is
preferably a nano-structure body.

[0062] The nano-structure body is a metal, a metal oxide, or a carbon
material or a combination of two or more of these materials having
nano-order diameter. The shortest diameter of the nano-structure body is
usually 1 nm or more and less than 1,000 nm. The shortest diameter of the
nano-structure body is preferably 800 nm or less, more preferably 600 nm
or less, further preferably 300 nm or less, particularly preferably 150
nm or less, and especially preferably 100 nm or less because electric
conductivity and dispersibility are improved.

[0063] The lowest limit of the shortest diameter of the nano-structure
body is usually 1 nm. The shortest diameter of the nano-structure body is
preferably 5 nm or more, more preferably 10 nm or more, and further
preferably 30 nm or more because electric conductivity is improved.

[0064] The longest diameter of the nano-structure body is usually 1,000 nm
or more, preferably 1,300 nm or more, more preferably 1,600 nm or more,
further preferably 2,000 nm or more, particularly preferably 2,500 nm or
more, and especially preferably 3,000 nm or more because electric
conductivity is improved. The longest diameter of the nano-structure body
is usually 1 cm or less, preferably 1 mm or less, more preferably 0.5 mm
or less, further preferably 0.3 mm or less, and especially preferably 0.1
mm or less.

[0065] From the characteristics of shapes, example of the nano-structure
body may include an anisotropic nano-particle, a nano-wire, a nano-tube,
a nano-rod, and a nano-sheet.

[0066] The nano-rod, the nano-tube, and the nano-wire are preferable as
the nano-structure body because these nano-structure bodies are easy to
be synthesized and can secure a sufficient aspect ratio. An aspect ratio
of the nano-rod is preferably 1.5 to 20 and more preferably 5 to 15. An
aspect ratio of the nano-wire is preferably 20 to 105 and more
preferably 100 to 104.

[0067] From the characteristics of shapes, examples of silver as the
conductive material of the cathode may include anisotropic silver
nano-particle, a silver nano-wire, a silver nano-tube, a silver nano-rod,
and a silver nano-sheet. The silver nano-rod, the silver nano-tube, and
the silver nano-wire are preferable because these silver nano-structure
bodies are easy to be synthesized and can secure a sufficient aspect
ratio.

[0068] The conductive material according to the present invention having
an aspect ratio of 1.5 or more is commercially available or can be
manufactured by using conventionally known methods. A liquid phase
method, a gas phase method, or the like can be used as the method for
manufacturing the conductive material having an aspect ratio of 1.5 or
more. The conductive material having an aspect ratio of 1.5 or more
manufactured by any methods may be used.

[0070] At the time of formation of the cathode by a coating method, a spin
coating method, a casting method, a microgravure coating method, a
gravure coating method, a bar coating method, a roll coating method, a
wire-bar coating method, a dip coating method, a spray coating method, a
screen printing method, a flexographic printing method, an offset
printing method, an ink-jet printing method, a capillary coating method,
and a nozzle coating method can be employed to form a film, when the film
made of a coating solution containing a conductive material having an
aspect ratio of 1.5 or more is formed by coating.

[0071] A solvent used for the coating solution is preferably a solvent
that can dissolve the material of the cathode or a solvent that can
homogeneously disperse the material of the cathode. Examples of the
solvent may include chlorinated hydrocarbon solvents such as chloroform,
methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane,
chlorobenzene, and o-dichlorobenzene; ether solvents such as
tetrahydrofuran and dioxane; aromatic hydrocarbon solvents such as
toluene and xylene; aliphatic hydrocarbon solvents such as cyclohexane,
methylcyclohexane, pentane, hexane, heptane, octane, nonane, and decane;
ketone solvents such as acetone, methyl ethyl ketone, and cyclohexanone;
ester solvents such as ethyl acetate, butyl acetate, and ethyl cellosolve
acetate; polyvalent alcohols and derivatives thereof such as ethylene
glycol, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether,
ethylene glycol monomethyl ether, dimethoxyethane, propylene glycol,
diethoxymethane, triethylene glycol monoethyl ether, glycerin, and
1,2-hexanediol; alcohol solvents such as methanol, ethanol, propanol,
isopropyl alcohol, and cyclohexanol; sulfoxide solvents such as
dimethylsulfoxide; and amide solvents such as N-methyl-2-pyrrolidone and
N,N-dimethylformamide. These solvents can be used singly or in
combination of two or more solvents.

[0072] The cathode has a single layer structure made of only one layer or
a stacked structure made of two or more or layers. When the cathode has a
stacked structure made of two or more layers, the cathode is formed by,
for example, sequentially stacking two or more layers using a coating
method or stacking two or more layers that is individually formed by a
casting method and the like by a lamination method.

[0073] The cathode 34 optionally contains an ionic compound other than the
conductive material having an aspect ratio of 1.5 or more.

[0074] Here, the ionic compound contains a cation and an anion. The ionic
compound optionally contains hydrated water and/or a neutral ligand. The
neutral ligand is a nonionic compound having a lone pair that can form a
coordinate bond. When the neutral ligand is bonded to the ionic compound,
the neutral ligand does not cause change in an oxidation number of the
ionic compound. Example of the compound that can be the neutral ligand
may include pyridine, 2,2'-bipyridyl, phenanthroline, terpyridine,
triphenylphosphine, carbon monoxide, and crown ethers.

[0075] Examples of the cation may include a metal cation, an organic
cation, and an ammonium cation. The metal cation is preferable as the
cation because the metal cation has excellent stability.

[0076] Examples of the metal cation may include an alkali metal cation, an
alkaline earth metal cation, a typical metal cation and a transition
metal cation. The alkali metal cation and the alkaline earth metal cation
are preferable as the metal cation.

[0077] Examples of the alkali metal cation may include Li.sup.+, Na.sup.+,
K.sup.+, Rb.sup.+, Cs.sup.+, and Fr.sup.+. Li.sup.+, Na.sup.+, K.sup.+,
Rb.sup.+ and Cs.sup.+ are preferable as the alkali metal cation, and
Cs.sup.+ is further preferable.

[0078] Examples of the alkaline earth metal cation may include Mg2+,
Ca2+, Sr2+, and Ba2+.

[0081] Examples of the organic cation may include onium cations having an
aromatic ring containing a nitrogen atom such as imidazolium cation and
pyridinium cation; an ammonium cation; and a phosphonium cation.

[0082] Examples of the anion may include F.sup.-, Cl.sup.-, Br.sup.-,
I.sup.-, OH.sup.-, CN.sup.-, NO3.sup.-, NO2.sup.-, ClO.sup.-,
ClO2.sup.-, ClO3.sup.-, ClO4.sup.-, CrO42-,
HSO4.sup.-, SCN.sup.-, BF4.sup.-, PF6.sup.-, an anion
represented by the formula: R3O.sup.-, an anion represented by the
formula: R4COO.sup.-, an anion represented by the formula:
R5SO3.sup.-, an anion represented by the formula:
R6OCO2.sup.-, an anion represented by the formula:
R7SO2.sup.-, an anion represented by the formula:
R8S.sup.-, an anion represented by the formula:
B(R9)4.sup.-, CO32-, S2-, S2-,
SO42-, S2O32-, PO43- and O2-. As
the anion, F.sup.-, Cl.sup.-, Br.sup.-, I.sup.-, OH.sup.-,
NO3.sup.-, BF4.sup.-, PF6.sup.-, the anion represented by
the formula: R3O.sup.-, the anion represented by the formula:
R4COO.sup.-, the anion represented by the formula:
R5SO3.sup.-, the anion represented by the formula:
R6CO3.sup.-, the anion represented by the formula:
R7SO2.sup.-, CO32-, SO42-, and
PO43- are preferable; F.sup.-, Cl.sup.-, Br.sup.-, OH.sup.-,
NO3.sup.-, BF4.sup.-, PF6.sup.-, the anion represented by
the formula: R3O.sup.-, the anion represented by the formula:
R4COO.sup.-, the anion represented by the formula:
R5SO3.sup.-, CO32-, and SO42- are more
preferable; F.sup.-, Cl.sup.-, Br.sup.-, I.sup.-, OH.sup.-,
NO3.sup.-, BF4.sup.-, PF6.sup.-, the anion represented by
the formula: R4COO.sup.-, the anion represented by the formula:
R5SO3.sup.-, CO32-, and SO42- are further
preferable; and F.sup.-, OH.sup.-, NO3.sup.-, the anion represented
by the formula: R4COO.sup.-, and CO32- are particularly
preferable.

[0083] In the formulae described above, R3, R4, R5,
R6, R7, R8, and R9 are each independently a
hydrocarbyl group optionally having a substituent.

[0084] Example of the hydrocarbyl group optionally having a substituent
and are represented by R3, R4, R5, R6, R7,
R8, and R9 may include alkyl groups having 1 to 50 carbon atoms
such as a methyl group, an ethyl group, a propyl group, an isopropyl
group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl
group, a pentyl group, a hexyl group, a nonyl group, a dodecyl group, a
pentadecyl group, an octadecyl group, and a docosyl group; cyclic
saturated hydrocarbyl groups having 3 to 50 carbon atoms such as a
cyclopropyl group, a cyclobutyl group, cyclopentyl group, a cyclohexyl
group, a cyclononyl group, a cyclododecyl group, a norbornyl group, and
an adamantyl group; alkenyl groups having 2 to 50 carbon atoms such as an
ethenyl group, a propenyl group, a 3-butenyl group, a 2-butenyl group, a
2-pentenyl group, a 2-hexenyl group, a 2-nonenyl group, and a 2-dodecenyl
group; aryl groups having 6 to 50 carbon atoms such as a phenyl group, a
1-naphthyl group, a 2-naphthyl group, a 2-methylphenyl group, a
3-methylphenyl group, a 4-methylphenyl group, a 4-ethylphenyl group, a
4-propylphenyl group, a 4-isopropylphenyl group, a 4-butylphenyl group, a
4-tert-butylphenyl group, a 4-hexylphenyl group, a 4-cyclohexylphenyl
group, a 4-adamantylphenyl group, and 4-phenylphenyl group; and arylalkyl
groups having 7 to 50 carbon atoms such as a phenylmethyl group, a
1-phenyleneethyl group, a 2-phenylethyl group, a 1-phenyl-1-propyl group,
a 1-phenyl-2-propyl group, a 2-phenyl-2-propyl group, a 3-phenyl-1-propyl
group, a 4-phenyl-1-butyl group, a 5-phenyl-1-pentyl group, and a
6-phenyl-1-hexyl group. As the hydrocarbyl group optionally having a
substituent, alkyl groups having 1 to 50 carbon atoms and aryl groups
having 6 to 50 carbon atoms are preferable; alkyl groups having 1 to 12
carbon atoms and aryl groups having 6 to 18 carbon atoms are more
preferable; and alkyl groups having 1 to 6 carbon atoms and aryl groups
having 6 to 12 carbon atoms are further preferable. Examples of the
substituent that the hydrocarbyl group may have may include an alkoxy
group, an aryloxy group, an amino group, an substituted amino group, a
silyl group, a substituted silyl group, a halogen atom, an imine residual
group, an amido group, an acid imido group, a monovalent heterocyclic
group, a mercapto group, a hydroxy group, a carboxy group, a cyano group,
and a nitro group. As the substituent that the hydrocarbyl group may
have, the amino group, the monovalent heterocyclic group, the mercapto
group, the hydroxy group, and the carboxy group are preferable, and the
amino group, a pyridyl group, the mercapto group, the hydroxy group, and
the carboxy group are more preferable. When the hydrocarbyl group has a
plurality of substituents, the substituents may be the same as or
different from each other.

[0085] The alkoxy group being a substituent that the hydrocarbyl group may
have may be a straight chain, a branched chain, or cyclic. The number of
carbon atoms in the alkoxy group is usually 1 to 20, and preferably 1 to
10. Examples of the alkoxy group that the hydrocarbyl group may have may
include a methoxy group, an ethoxy group, a propyloxy group, an
isopropyloxy group, a butoxy group, an isobutoxy group, a sec-butoxy
group, a tert-butoxy group, a pentyloxy group, a hexyloxy group, a
cyclohexyloxy group, a heptyloxy group, an octyloxy group, a nonyloxy
group, a decyloxy group, and a lauryloxy group. Hydrogen atoms in the
alkoxy group that the hydrocarbyl group may have are optionally
substituted by fluorine atoms. Examples of the alkoxy group substituted
by fluorine atoms may include a trifluoromethoxy group, a
pentafluoroethoxy group, a perfluorobutoxy group, a perfluorohexyloxy
group, a perfluorooctyloxy group, a methoxymethyloxy group, and a
2-methoxyethyloxy group.

[0086] The number of carbon atoms in the aryloxy group being a substituent
that the hydrocarbyl group may have is usually 6 to 60, and preferably 6
to 48. Examples of the aryloxy group that the hydrocarbyl group may have
may include a phenoxy group, a C1-C12 alkoxyphenoxy group
(here, C represents a carbon atom. The subscript number represents the
number of carbon atoms. The description "C1-C12" represents
that the number of carbon atoms is 1 to 12. The same will apply
hereinafter), a C1-C12 alkylphenoxy group, a 1-naphthyloxy
group, a 2-naphthyloxy group, and a pentafluorophenyloxy group.

[0087] Examples of the C1-C12 alkoxyphenoxy group may include a
methoxyphenoxy group, an ethoxyphenoxy group, a propyloxyphenoxy group,
an isopropyloxyphenoxy group, a butoxyphenoxy group, an isobutoxyphenoxy
group, a sec-butoxyphenoxy group, a tert-butoxyphenoxy group, a
pentyloxyphenoxy group, a hexyloxyphenoxy group, a cyclohexyloxyphenoxy
group, a heptyloxyphenoxy group, an octyloxyphenoxy group, a
2-ethylhexyloxyphenoxy group, a nonyloxyphenoxy group, a decyloxyphenoxy
group, a 3,7-dimethyloctyloxyphenoxy group, and a lauryloxyphenoxy group.

[0088] Examples of the C1-C12 alkylphenoxy group may include a
methylphenoxy group, an ethylphenoxy group, a dimethylphenoxy group, a
propylphenoxy group, 1,3,5-trimethylphenoxy group, a methylethylphenoxy
group, an isopropylphenoxy group, a butylphenoxy group, an
isobutylphenoxy group, a sec-butylphenoxy group, a tert-butylphenoxy
group, a pentylphenoxy group, an isoamylphenoxy group, a hexylphenoxy
group, a heptylphenoxy group, an octylphenoxy group, a nonylphenoxy
group, a decylphenoxy group, and a dodecylphenoxy group.

[0089] Examples of the substituted amino group being a substituent that
the hydrocarbyl group may have may include an amino group in which one or
more hydrogen atoms in the amino group are substituted by one or more
groups selected from the group consisting of an alkyl group, an aryl
group, an arylalkyl group, and a monovalent heterocyclic group. The
number of carbon atoms in the substituted amino group is usually 1 to 60,
and preferably 2 to 48. Examples of the substituted amino group that the
hydrocarbyl group may have may include a methylamino group, a
dimethylamino group, an ethylamino group, a diethylamino group, a
propylamino group, a dipropylamino group, an isopropylamino group, a
diisopropylamino group, a butylamino group, an isobutylamino group, a
sec-butylamino group, a tert-butylamino group, a pentylamino group, a
hexylamino group, a cyclohexylamino group, a heptylamino group, an
octylamino group, a 2-ethylhexylamino group, a nonylamino group, a
decylamino group, a 3,7-dimethyloctylamino group, a laurylamino group, a
cyclopentylamino group, a dicyclopentylamino group, a cyclohexylamino
group, a dicyclohexylamino group, a pyrrolidyl group, a piperidyl group,
a ditrifluoromethylamino group, a phenylamino group, a diphenylamino
group, a C1-C12 alkoxyphenylamino group, a di(C1-C12
alkoxyphenyl)amino group, a di(C1-C12 alkylphenyl)amino group,
a 1-naphthylamino group, a 2-naphthylamino group, a
pentafluorophenylamino group, a pyridylamino group, a pyridazinylamino
group, a pyrimidylamino group, a pyrazylamino group, a triazylamino
group, a phenyl-C1-C12 alkylamino group, a C1-C12
alkoxyphenyl-C1-C12 alkylamino group, a C1-C12
alkylphenyl-C1-C12 alkylamino group, a di(C1-C12
alkoxyphenyl-C1-C12 alkyl)amino group, a di(C1-C12
alkylphenyl-C1-C12 alkyl)amino group, a
1-naphthyl-C1-C12 alkylamino group, and a
2-naphthyl-C1-C12 alkylamino group.

[0090] Examples of the substituted silyl group being a substituent that
the hydrocarbyl group may have may include a silyl group in which one or
more hydrogen atoms in the silyl group are substituted by one or more
groups selected from the group consisting of an alkyl group, an aryl
group, an arylalkyl group, and a monovalent heterocyclic group. The
number of carbon atoms in the substituted silyl group is usually 1 to 60,
and preferably 2 to 48.

[0091] Examples of the halogen atom being a substituent that the
hydrocarbyl group may have may include a fluorine atom, a chlorine atom,
a bromine atom, and an iodine atom.

[0092] The imine residual group being a substituent that the hydrocarbyl
group may have refers to a residual group in which, from an imine
compound having a structure represented by the formula: H--N═C< or
the formula: --N═CH--, one hydrogen atom is eliminated from this
structure. Examples of the imine compound may include aldimine, ketimine,
and a compound that is made by substituting a hydrogen atom bonded to a
nitrogen atom in aldimine with an alkyl group, an aryl group, an
arylalkyl group, an arylalkenyl group, and an arylalkynyl group. The
number of carbon atoms in the imine residual group is usually 2 to 20,
and preferably 2 to 18. Examples of the imine residual group that the
hydrocarbyl group may have may include a group represented by the general
formula: --CR.sup.β═N--R.sup.γ or the general formula:
--N═C(R7)2. In the general formula, R.sup.β represents
a hydrogen atom, an alkyl group, an aryl group, an arylalkyl group, an
arylalkenyl group, and an arylalkynyl group, and R.sup.γs
independently represent an alkyl group, an aryl group, an arylalkyl
group, an arylalkenyl group, and an arylalkynyl group when two
R.sup.γs exist. When two R.sup.γs exist, however, the two
R.sup.γs may be bonded to each other to integrally form a ring as a
divalent group, for example, an alkylene group having 2 to 18 carbon
atoms such as an ethylene group, a trimethylene group, a tetramethylene
group, pentamethylene group, and hexamethylene group. The following
groups are included as the imine residual group that the hydrocarbyl
group may have.

##STR00007##

[0093] In these formulae, Me represents a methyl group, and the same will
apply hereinafter.

[0094] The number of carbon atoms in the amido group being a substituent
that the hydrocarbyl group may have is usually 1 to 20, and preferably 2
to 18. Examples of the amido group that the hydrocarbyl group may have
may include a formamido group, an acetamido group, a propionamido group,
a butyramido group, a benzamido group, a trifluoroacetamido group, a
pentafluorobenzamido group, a diformamido group, a diacetamido group, a
dipropionamido group, a dibutyramido group, a dibenzamido group, a
ditrifluoroacetamido group, and a dipentafluorobenzamido group.

[0095] The acid imido group being a substituent that the hydrocarbyl group
may have is a residual group obtained by eliminating a hydrogen atom
bonded to a nitrogen atom of an acid imide from the acid imide. The
number of carbon atoms in the acid imido group is usually 4 to 20, and
preferably 4 to 18. The follwoing groups are included as examples of the
acid imido group.

##STR00008##

[0096] The monovalent heterocyclic group being a substituent that the
hydrocarbyl group may have is a residual atom group in which one hydrogen
atom is eliminated from the heterocyclic compound optionally having a
substituent. Examples of the hetero ring of the heterocyclic compound may
include monocyclic heterocycles such as a pyridine ring, a 1,2-diazine
ring, a 1,3-diazine ring, a 1,4-diazine ring, a 1,3,5-triazine ring, a
furan ring, a pyrrole ring, a thiophene ring, a pyrazole ring, an
imidazole ring, an oxazole ring, a thiazole ring, an oxadiazole ring, a
thiadiazole ring, an azadiazole ring; a fused multicyclic hetero ring in
which two or more rings selected from monocyclic aromatic rings are
fused; and a crosslinkage-containing multicyclic aromatic ring having a
structure in which two hetero rings, or one hetero ring and one aromatic
ring are crosslinked through a divalent group such as a methylene group,
an ethylene group and a carbonyl group. As the hetero rings, the pyridine
ring, the 1,2-diazine ring, the 1,3-diazine ring, the 1,4-diazine ring,
and the 1,3,5-triazine ring are preferable, and the pyridine ring and the
1,3,5-triazine ring are more preferable.

[0097] The ionic compound preferably has a structure represented by the
following formula (h-1).

Mm'+aX'n'-b (h-1)

[0098] In formula (h-1), Mm'+ represents a metal cation. X'n'-
represents an anion. a and b are each independently an integer of 1 or
more. When Mm'+ and X'n'- are each plurally present, each
Mm'+ and X'n'- may be the same as or different from each other.

[0099] The ionic compound represented by formula (h-1) optionally contains
hydrated water and/or a neutral ligand that is described above.

[0100] In formula (h-1), preferable a and b are each independently an
integer of 1 to 3, and more preferably 1 or 2. Here, a and b are a
combination having no charge disproportionation as a whole of the ionic
compound represented by formula (h-1).

[0101] In formula (h-1), m' represents an integer of 1 or more.
Definition, specific examples, and preferable examples of the metal
cation represented by Mm'+ are as described above.

[0102] In formula (h-1), n' represents an integer of 1 or more.
Definition, specific examples, and preferable examples of the anion
represented by X'n- are as described above.

[0103] When the ionic compound contains the hydrated water, the ionic
compound preferably has a structure represented by the following formula
(h-2).

Mm'+aX'n'-b.n''(H2O) (h-2)

[0104] In formula (h-2), n'' represents an integer of 1 or more.
Definition, specific examples, and preferable examples of Mm'+,
X'n'-, a and b are as described above.

[0107] The ionic compound may be used singly or in combination of two or
more compounds. A molecular weight of the ionic compound is preferably
less than 1,000, more preferably less than 800, further preferably less
than 500, and particular preferably less than 300.

[0108] The amount of added ionic compound in the cathode 34 of the
light-emitting device of the present invention is usually 0.01 parts by
weight or more and 1,000 parts by weight or less, preferably 0.1 parts by
weight or more and 100 parts by weight or less, and more preferably 1
part by weight or more and 50 parts by weight or less, with respect to
100 parts by weight of the material of the cathode.

[0109] Any other materials can be mixed with the material for the cathode
with the proviso that conductivity of the cathode 34 is not seriously
impaired. When the material for the cathode is used by mixing with other
materials, these materials may be mixed before the cathode 34 is formed,
or may be mixed after the cathode 34 is formed.

[0110] The cathode 34 of the light-emitting device is preferably has
optical transparency. The light-emitting device can emit light from a
side closer to the cathode by using the cathode having the optical
transparency. The aspect ratio of the conductive material is preferably
10 or more, more preferably 50 or more, further preferably 100 or more,
and particularly preferably 300 or more because the optical transparency
of the cathode is improved. When the aspect ratio is less than 1.5, the
optical transparency may be deteriorated.

[0111] The optical transparency can be measured by using total light
transmittance. In the present invention, "a cathode has optical
transparency" means that a total light transmittance of the cathode is
40% or more. The total light transmittance is preferably 60% or more,
further preferably 70% or more, and particularly preferably 80% or more
because the characteristics of the light-emitting device are improved.

[0112] A thickness of the cathode 34 can be adjusted in consideration of
electric conductivity and, in particular, light transparency when the
cathode has optical transparency. The thickness of the cathode 34 is
preferably 10 nm or more, more preferably 20 nm or more, further
preferably 50 nm or more, and particularly preferably 100 nm or more. In
addition, the thickness of the cathode 34 is preferably 30 μm or less,
more preferably 10 μm or less, further preferably 5 μm or less,
particularly preferably 1 μm or less, and especially preferably 500 nm
or less.

[0113] Preferably, the surface of the cathode formed by the coating method
is smooth and has less concavity and convexity. A height difference
between a higher part (a convex part) and a lower part (a concave part)
in the concavity and convexity of the surface of the cathode is
preferably 1 μm or less, more preferably 100 nm or less, particularly
preferably 50 nm or less, especially preferably 20 nm or less, and
extremely preferably 10 nm or less.

[0114] Examples of methods reducing the concavity and convexity of the
surface of the cathode may include a method in which a film formed by
coating is heated at a temperature of the melting point of the conductive
material or higher; a method in which pressure is applied to the surface
of a film formed by coating; a method in which a film once formed by
applying a coating solution on a provisional substrate is transferred
onto a given substrate; and a method in which other material is filled in
the concave portion of a film formed by coating.

[0115] --Anode--

[0116] In the light-emitting device 10, the anode 32 can be formed on the
substrate using a material for the anode. The anode can be formed by
preparing a substrate in which a conductive thin film formed by using a
conductive material such as ITO is previously provided, and patterning
the conductive thin film with a prescribed pattern.

[0117] A material constituting the anode 32 is preferably contains a
conductive material having an aspect ratio of 1.5 or more. Definition,
specific examples, and preferable examples of the conductive material
having an aspect ratio of 1.5 or more that can be used as a material for
the anode are the same as the definition, the specific examples, and the
preferable examples of the conductive material having an aspect ratio of
1.5 or more used in the cathode as described above.

[0118] Examples of the material constituting the anode 32 may include a
conductive metal oxide, a metal, a carbon material, and a conductive
polymeric material. Examples of the material for the anode may include
the metal oxides such as indium oxide, zinc oxide, tin oxide and mixtures
thereof such as ITO, AZO, IZO, and NESA; the metals such as gold,
platinum, silver, and copper; the carbon materials such as carbon
nanotube and graphite; and the conductive polymeric materials such as
conductive polymers including polyaniline, polythiophene (for example,
poly(3,4-ethylenedioxythiophen)/polystyrene sulfonic acid), and
polypyrrole, and polymers including these conductive polymers. The anode
is a single layer structure made of only one layer or a stacked structure
made of two or more layers.

[0119] A thickness of the anode 32 can be adjusted in consideration of
electric conductivity and durability. The thickness of the anode is
usually 10 nm or more, preferably 20 nm or more, more preferably 50 nm or
more, and further preferably 100 nm or more. In addition, the thickness
of the anode 32 is usually 10 μm or less, preferably 1 μm or less,
and more preferably 500 nm or less.

[0120] Examples of methods for forming the anode 32 may include a vacuum
evaporation method, a sputtering method, a lamination method in which a
thin metal film is laminated by thermocompression, or a coating method.
The coating method is preferable as the method for forming the anode 32.
A layer made of a conductive polymeric material, or layer made of a metal
oxide, a metal fluoride, or an organic insulation material may be
provided between the anode 32 and the electron injection layer 44.

[0121] When a coating method in which a coating solution is applied is
used as the method for forming the anode 32, examples of the solvent used
for the coating solution are the same as the solvent used for the coating
solution when the cathode is formed by the coating method as described
above.

[0122] The anode 32 may contain an ionic compound other than the material
for the anode. Definition, specific examples, and preferable examples of
the ionic compound used with the material for the anode are the same as
the definition, the specific examples, and the preferable examples of the
ionic compound in the material used in the cathode as described above.

[0123] The ionic compound may be used singly or in combination of two or
more compounds. A molecular weight of the ionic compound is preferably
less than 1,000, more preferably less than 800, further preferably less
than 500, and particularly preferably less than 300.

[0124] The amount of added ionic compound in the anode 32 of the
light-emitting device of the present invention is usually 0.01 parts by
weight or more and 1,000 parts by weight or less, preferably 0.1 parts by
weight or more and 100 parts by weight or less, and more preferably 1
part by weight or more and 50 parts by weight or less, with respect to
100 parts by weight of the material of the anode.

[0125] Any other materials can be mixed with the material for the anode
with proviso that conductivity of the anode 32 is not seriously impaired.
Other materials may be mixed before the anode 32 is formed, or may be
mixed after the anode 32 is formed.

[0126] In the present invention, a layer having a function as an anode
even when the layer is formed by a composition that is made by mixing a
material for the anode and the other materials is the anode.

[0127] The conductive polymeric material is preferable as a material that
may be mixed with the material for the anode. Examples of the conductive
polymeric material may include polyfluorene and a derivative thereof,
polythiophene and a derivative thereof, polyaniline and a derivative
thereof, polypyrrole and a derivative thereof, and polyphenylamine and a
derivative thereof.

[0128] A hole injection material is preferable as the other material that
may be mixed with the material for the anode. A layer formed by a
composition made by mixing the material for the anode and the hole
injection material is a layer having both functions of the hole injection
layer and the anode. The layer formed by the composition made by mixing
the material for the anode and the hole injection material may be
referred to as an anode containing the hole injection material.

[0129] Preferably, the surface of the anode 32 formed by the coating
method is smooth and has less concavity and convexity. A height
difference between a convex portion and a concave portion in the
concavity and convexity of the surface of the anode is preferably 1 μm
or less, more preferably 100 nm or less, particularly preferably 50 nm or
less, especially preferably 20 nm or less, and extremely preferably 10 nm
or less.

[0130] Examples of methods reducing the concavity and convexity of the
surface of the anode 32 may include a method in which a film formed by
coating is heated at a temperature of the melting point of the conductive
material or higher; a method in which pressure is applied to the surface
of a film formed by coating; a method in which a film once formed by
applying a coating solution on a provisional substrate is transferred
onto a given substrate; and a method in which other material is filled in
the concave portion of a film formed by coating.

[0131] At least one of the cathode 34 and the anode 32 preferably contains
the conductive material having an aspect ratio of 1.5 or more. Both of
the cathode 34 and the anode 32 can contain the conductive material
having an aspect ratio of 1.5 or more. Preferably, the cathode 34
contains the conductive material having an aspect ratio of 1.5 or more.

[0132] --Electron Injection Layer--

[0133] The electron injection layer 44 includes an organic compound
containing at least one of an ionic group and a polar group. More
preferably, the electron injection layer 44 contains an organic compound
having both the ionic group and the polar group. The organic compound is
preferably a conjugated compound, and more preferably an aromatic
compound. The electron injection layer 44 is a single layer structure
made of only one layer or a stacked structure made of two or more layers.

[0134] In this specification, the conjugated compound refers to a compound
having a conjugated system. As the conjugated compound, a compound
including a system in which a single bond is continuously connected to a
multiple bond (a double bond and a triple bond); unshared electron pairs
of a nitrogen atom, an oxygen atom, a sulfur atom, or a phosphorus atom;
a vacant p orbital that a boron atom has; or a d orbital for a sigma
bonding that a silicon atom has, so that the single bond is interposed by
them. An electron transport characteristic is improved in these
conjugated compounds. Therefore, a value (%) calculated by the following
formula is preferably 50% or more, more preferably 60% or more, more
preferably 70% or more, further preferably 80% or more, and particularly
preferably 90% or more. Aromatic compounds are especially preferably as
the conjugated compound.

[0135] Formula: {(The number of atoms in a mother skeleton or a main chain
contained in a region where a single bond is interposed between a
multiple bond; unshared electron pairs of a nitrogen atom, an oxygen
atom, a sulfur atom, or a phosphorus atom; a vacant p orbital that a
boron atom has; or a d orbital for a sigma bonding that a silicon atom
has and this structure continuously connects)/(The number of total atoms
in the mother skeleton or the main chain)}×100

[0136] The organic compound having at least one of the ionic group and the
polar group contained in the electron injection layer may be used by
mixing two or more organic compounds.

[0137] Examples of the ionic group that the organic compound contained in
the electron injection layer has may include a group represented by the
formula: --SM, a group represented by the formula: --C(═O)SM, a group
represented by the formula: --CS2M, a group represented by the
formula: --OM, a group represented by the formula: --CO2M, a group
represented by the formula: --NM2, a group represented by the
formula: --NRM, a group represented by the formula: --PO3M, a group
represented by the formula: --OP(═O)(OM)2, a group represented
by the formula: --P(═O)(OM)2, a group represented by the
formula: --C(═O)NM2, a group represented by the formula:
--C(═O)NRM, a group represented by the formula: --C(═S)NRM, a
group represented by the formula: --C(═S)NM2, a group
represented by the formula: --B(OM)2, a group represented by the
formula: --BR3M, a group represented by the formula: --B(OR)3M,
a group represented by the formula: --SO3M, a group represented by
the formula: --SO2M, a group represented by the formula:
--NRC(═O)OM, a group represented by the formula: --NRC(═O)SM, a
group represented by the formula: --NRC(═S)OM, a group represented by
the formula: --NRC(═S)SM, a group represented by the formula:
--OC(═O)NM2, a group represented by the formula:
--OC(═O)NRM, a group represented by the formula:
--OC(═S)NM2, a group represented by the formula:
--OC(═S)NRM, a group represented by the formula:
--SC(═O)NM2, a group represented by the formula:
--SC(═O)NRM, a group represented by the formula:
--SC(═S)NM2, a group represented by the formula:
--SC(═S)NRM, a group represented by the formula:
--NRC(═O)NM2, a group represented by the formula:
--NRC(═O)NRM, a group represented by the formula:
--NRC(═S)NM2, a group represented by the formula:
--NRC(═S)NRM, a group represented by the formula: --NR3M', a
group represented by the formula: --PR3M', a group represented by
the formula: --OR2M', a group represented by the formula:
--SR2M', a group represented by the formula: --IRM', a group made by
a residual atom group represented by eliminating a hydrogen atom from an
aromatic ring selected from the aromatic compounds represented by
following formula (n-1) to formula (n-13) (In formulae, R represents a
hydrogen atom or a hydrocarbyl group optionally having a substituent, M
represents a metal cation or an ammonium cation that may have a
substituent, and M' represents an anion).

##STR00009## ##STR00010##

[0138] Other metal cation other than the metal cation represented by M may
be accompanied or an anion may be accompanied in these groups so that
charge of the total ionic groups is balanced to be zero.

[0139] The hydrocarbyl group optionally having a substituent represented
by R is a similar group to the hydrocarbyl group optionally having a
substituent represented by R3 to R9.

[0140] A monovalent, a divalent or a trivalent ion is preferable as the
metal cation represented by M. Examples of the metal cation represented
by M may include ions of metals such as Li, Na, K, Cs, Be, Mg, Ca, Ba,
Ag, Al, Bi, Cu, Fe, Ga, Mn, Pb, Sn, Ti, V, W, Y, Yb, Zn, and Zr. As the
metal cation represented by M, ions of Li, Na, K, Cs, Mg, Ca, Ag, and Al
are preferable; ions of Li, Na, K, Cs, Mg, and Ca are more preferable;
and ions of Li, Na, K, and Cs are further preferable.

[0141] Examples of a substituent that an ammonium cation represented by M
may have may include alkyl groups having 1 to 10 carbon atoms such as a
methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl
group, an isobutyl group, a sec-butyl group, and a tert-butyl group.

[0143] Preferable examples of the ionic group may include the group
represented by the formula: --SM, the group represented by the formula:
--OM, the group represented by the formula: --CO2M, the group
represented by the formula: --NM2, the group represented by the
formula: --NRM, the group represented by the formula: --PO3M, the
group represented by the formula: --OP(═O)(OM)2, the group
represented by the formula: --P(═O)(OM)2, the group represented
by the formula: --C(═O)NM2, the group represented by the
formula: --C(═O)NRM, the group represented by the formula:
--SO3M, the group represented by the formula: --SO2M, the group
represented by the formula: --NR3M', and the group represented by
formula (n-1), formula (n-5) to formula (n-8), and formula (n-13). More
preferable examples of the ionic group may include the group represented
by the formula: --CO2M, the group represented by the formula:
--PO3M, the group represented by the formula:
--OP(═O)(OM)2, the group represented by the formula:
--P(═O)(OM)2, the group represented by the formula: --SO3M,
the group represented by the formula: --SO2M, the group represented
by the formula: --NR3M', and the group represented by formula (n-1),
formula (n-5), and formula (n-13). Further preferable examples of the
ionic group may include the group represented by the formula:
--CO2M, the group represented by the formula: --SO3M, the group
represented by the formula: --SO2M, the group represented by the
formula: --NR3M', and the group represented by formula (n-1) and
formula (n-5). Particularly preferable examples of the ionic group may
include the group represented by the formula: --CO2M and the group
represented by the formula: --SO3M. Especially preferable example of
the ionic group may include the group represented by the formula:
--CO2M.

[0144] Examples of the polar group that the organic compound contained in
the electron injection layer has may include a carboxy group, a sulfo
group, a hydroxy group, a mercapto group, an amino group, a
hydrocarbylamino group, a cyano group, a pyrrolidonyl group, a monovalent
heterocyclic group, and a group represented by the following formula (I)
to formula (IX).

--O--(R'O)m--R'' (I)

##STR00011## --S--(R'S)q--R'' (III)

--C(═O)--(R'--C(═O))q--R'' (IV)

--C(═S)--(R'--C(═S))q--R'' (V)

--N{(R')qR''}2 (VI)

--C(═O)O--(R'--C(═O)O)q--R'' (VII)

--C(═O)--O--(R'O)q--R'' (VIII)

--NHC(═O)--(R'NHC(═O))q--R'' (IX)

[0145] In formula (I) to formula (IX), R' represents a hydrocarbylene
group optionally having a substituent. R'' represents a hydrogen atom, a
hydrocarbyl group optionally having a substituent, a carboxy group, a
sulfo group, hydroxy group, a mercapto group, an amino group, a group
represented by --NRc2, a cyano group, or group represented by
--C(═O)NRc2. R''' represents a trivalent hydrocarbon group
optionally having a substituent. m represents an integer of 1 or more. q
represents an integer of zero or more. Rc represents an alkyl group
having 1 to 30 carbon atoms optionally having a substituent, or an aryl
group having 6 to 50 carbon atoms optionally having a substituent. When
R', R'', and R''' are each plurally present, each R', R'', and R''' may
be the same as or different from each other.

[0146] The hydrocarbylamino group is an amino group in which one of the
hydrogen atoms constituting the amino group is substituted by a
hydrocarbyl group optionally having a substituent. Examples of the
hydrocarbylamino group may include a methylamino group, an ethylamino
group, a propylamino group, an isopropylamino group, a butylamino group,
an isobutylamino group, a sec-butylamino group, a tert-butylamino group,
a pentylamino group, a hexylamino group, a heptylamino group, an
octylamino group, a 2-ethylhexylamino group, a nonylamino group, a
decylamino group, a 3,7-dimethyloctylamino group, a dodecylamino group, a
trifluoromethylamino group, a phenylamino group, a 1-naphthylamino group,
a 2-naphthylamino group, 2-methylphenylamino group, a 3-methylphenylamino
group, a 4-methylphenylamino group, a 4-ethylphenylamino group, a
4-propylphenylamino group, a 4-isopropylphenylamino group, a
4-butylphenylamino group, a 4-tert-butylphenylamino group, a
4-hexylphenylamino group, a 4-cyclohexylphenylamino group, a
4-adamantylphenylamino group, and a 4-phenylphenylamino group.

[0147] The monovalent heterocyclic group is a similar group to the
monovalent heterocyclic group being a substituent that the hydrocarbyl
group represented by R3 to R9 as previously described can have.

[0148] In formula (I) to formula (IX), examples of the hydrocarbylene
group represented by R' may include saturated hydrocarbylene groups
having 1 to 50 carbon atoms such as a methylene group, an ethylene group,
a 1,2-propylene group, a 1,3-propylene group, a 1,2-butylene group, a
1,3-butylene group, a 1,4-butylene group, a 1,5-pentylene group, a
1,6-hexylene group, a 1,9-nonylene group, and a 1,12-dodecylene group;
unsaturated hydrocarbylene groups having 2 to 50 carbon atoms such as an
ethenylene group, a propenylene group, a 3-butenylene group, a
2-pentenylene group, a 2-hexenylene group, a 2-nonenylene group, and a
2-dodecenylene group; cyclic saturated hydrocarbylene groups having 3 to
50 carbon atoms such as a cyclopropylene group, a cyclobutylene group, a
cyclopentylene group, a cyclohexylene group, a cyclononylene group, a
cyclodocecylene group, a norbornylene group, and an adamantylene group;
alkenylene groups having 2 to 50 carbon atoms such as an ethenylene
group, a propenylene group, a 3-butenylene group, a 2-butenylene, a
2-pentenylene group, a 2-hexenylene group, a 2-nonenylene group, and a
2-dodecenylene group; and arylene groups having 6 to 50 carbon atoms such
as a 1,3-phenylene group, 1,4-phenylene, a 1,4-naphthylene group, a
1,5-naphthylene group, a 2,6-naphthylene group, and a biphenyl-4,4'-diyl
group.

[0149] R' may have a substituent. The substituent may be the same as the
substituent that the hydrocarbyl group represented by R3 to R9
as previously described can have.

[0150] When the substituents are plurally present, the substituents may be
the same as or different from each other.

[0151] Examples of the hydrocarbyl group represented by R'' in formula (I)
to formula (IX) may include alkyl groups having 1 to 20 carbon atoms such
as a methyl group, an ethyl group, a propyl group, an isopropyl group, a
butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a
pentyl group, a hexyl group, a cyclohexyl group, a heptyl group, an octyl
group, a nonyl group, a decyl group, and a lauryl group; and aryl groups
having 6 to 30 carbon atoms such as a phenyl group, a 1-naphthyl group, a
2-naphthyl group, a 1-anthracenyl group, a 2-anthracenyl group, and a
9-anthracenyl group. Since solubility of a solvent is excellent, the
methyl group, the ethyl group, the phenyl group, the 1-naphthyl group,
and the 2-naphthyl group are preferable as R''. R'' may have a
substituent. As the substituent, the same substituent as the substituent
that the hydrocarbyl group represented by R3 to R9 as
previously described can have may be included. When the substituents are
plurally present, the substituents may be the same as or different from
each other.

[0152] In formula (I) to formula (IX), a trivalent hydrocarbon group
represented by R''' and optionally having a substituent is usually a
group having 1 to 50 carbon atoms and preferably a group having 1 to 30
carbon atoms. Examples of the trivalent hydrocarbon group optionally
having a substituent may include unsubstituted alkanetriyl groups having
1 to 20 carbon atoms such as a methanetriyl group, an ethanetriyl group,
a 1,2,3-propanetriyl group, a 1,2,4-butanetriyl group, a
1,2,5-pentanetriyl group, a 1,3,5-pentanetriyl group, a 1,2,6-hexanetriyl
group, and a 1,3,6-hexanetriyl group, and substituted alkanetriyl groups
in which at least one hydrogen atom in these groups is substituted;
unsubstituted trivalent aromatic ring groups having 6 to 30 carbon atoms
such as a 1,2,3-benzenetriyl group, a 1,2,4-benzenetriyl group, and a
1,3,5-benzenetriyl group, and groups in which at least one hydrogen atom
in these groups is substituted. Since solubility of the conjugated
compound into the solvent is excellent, the methanetriyl group, the
ethanetriyl group, the 1,2,4-benzenetriyl group, and the
1,3,5-benzenetriyl group are preferable.

[0153] In formula (I) to formula (IX), since solubility of the solvent is
excellent, a methyl group, a ethyl group, a phenyl group, a 1-naphthyl
group, and a 2-naphthyl group are preferable as Rc.

[0154] In formula (I) and formula (II), m represents an integer of 1 or
more. m is preferably 1 to 20, more preferably 3 to 20, further
preferably 3 to 15, and particularly preferably 6 to 10.

[0155] In formula (III) to formula (IX), q represents an integer of 0 or
more. In formula (III), q is preferably 0 to 30, more preferably 3 to 20,
further preferably 3 to 10, and particularly preferably 6 to 10. In
formula (IV) to formula (VII), q is preferably 0 to 30, more preferably 0
to 20, further preferably 0 to 10, and particularly preferably 0 to 5. In
formula (VIII), q is preferably 0 to 30, more preferably 0 to 20, further
preferably 3 to 20, and particularly preferably 3 to 10. In formula (IX),
q is preferably 0 to 30, more preferably 0 to 20, further preferably 0 to
15, and particularly preferably 0 to 10.

[0156] Preferable examples of the polar group may include a carboxy group,
a sulfo group, hydroxy group, a mercapto group, an amino group, a
hydrocarbylamino group, a cyano group, a pyrrolidonyl group, a monovalent
heterocyclic group, a group represented by formula (I), and a group
represented by formula (II). More preferable examples may include the
carboxy group, the sulfo group, the hydroxy group, the mercapto group,
the amino group, the hydrocarbylamino group, the cyano group, the
pyrrolidonyl group, a pyridyl group, a 1,3,5-triazyl group, and the group
represented by formula (I). Further preferable examples may include the
carboxy group, the sulfo group, the mercapto group, the amino group, the
pyrrolidonyl group, the pyridyl group, and the group represented by
formula (I). Particularly preferable examples may include the carboxy
group, the mercapto group, the amino group, the pyrrolidonyl group, the
pyridyl group, and the group represented by formula (I). Especially
preferable examples may include the carboxy group, the mercapto group,
the pyridyl group, and the group represented by formula (I). Extremely
preferable example may include the group represented by formula (I).

[0157] The conjugated compound that the electron injection layer 44
contains preferably has, for example, a group represented by formula (X)
or a structural unit represented by formula (XI), or has both of them.

##STR00012##

[0158] In formula (X), Ar1 represents an aromatic group having a
valence of (n1+1). R1 represents a direct bond or a group
having a valence of (m1+1). X1 represents a group having at
least one of an ionic group and a polar group. m1 and n1 are
each independently an integer of 1 or more. When R1 is a direct
bond, m1 is 1. When R1, X1 and m1 are each plurally
present, each R1, X1, and m1 may be the same as or
different from each other.

##STR00013##

[0159] In formula (XI), Ar2 represents an aromatic group having a
valence of (n2+2); R2 represents a direct bond or a group
having a valence of (m2+1); and X2 represents a group having at
least one of an ionic group and a polar group. m2 and n2 are
each independently an integer of 1 or more; when R2 is a direct
bond, m2 is 1. When R2, X2 and m2 are each plurally
present, each R2, X2 and m2 may be the same as or
different from each other.

[0160] In formula (X), an aromatic group represented by Ar1 having a
valence of (n1+1) refers to a residual atom group (a residual group)
in which (n1+1) hydrogen atoms are eliminated from an aromatic ring
in the aromatic compound having the aromatic ring, and a group optionally
having a substituent.

[0161] In formula (XI), an aromatic group represented by Ar2 having a
valence of (n2+2) means a residual atom group (a residual group) in
which (n2+2) hydrogen atoms are eliminated from an aromatic ring in
the aromatic compound having the aromatic ring, and a group optionally
having a substituent.

[0163] One or more hydrogen atoms in these aromatic compounds may be
substituted by a substituent. Examples of the substituent may include a
halogen atom, a hydrocarbyl group optionally having a substituent, a
mercapto group, a mercaptocarbonyl group, a mercaptothiocarbonyl group, a
hydrocarbylthio group optionally having a substituent, a
hydrocarbylthiocarbonyl group optionally having a substituent, a
hydrocarbyldithio group optionally having a substituent, a hydroxy group,
a hydrocarbyloxy group optionally having a substituent, a carboxy group,
a hydrocarbylcarbonyl group optionally having a substituent, an amino
group, a hydrocarbylamino group in which hydrogen(s) in the hydrocarbyl
group may be substituted by substituent(s), an dihydrocarbylamino group
in which hydrogen(s) in the hydrocarbyl group may be substituted by
substituent(s), a phosphino group, a hydrocarbylphosphino group in which
hydrogen(s) in the hydrocarbyl group may be substituted by
substituent(s), a dihydrocarbylphosphino group in which hydrogen(s) in
the hydrocarbyl group may be substituted by substituent(s), a monovalent
heterocyclic group, a formyl group, a hydrocarbyloxycarbonyl group
optionally having a substituent, a hydrocarbylcarbonyloxy group
optionally having a substituent, a nitro group, a group represented by
the formula: --OP(═O)(OH)2, a group represented by the formula:
--P(═O)(OH)2, a carbamoyl group, a hydrocarbylcarbamoyl group in
which hydrogen(s) in the hydrocarbyl group may be substituted by
substituent(s), a dihydrocarbylcarbamoyl group in which hydrogen(s) in
the hydrocarbyl group are optionally substituted by substituent(s), a
group represented by the formula: --C(═S)NR2, a group
represented by the formula: --B(OH)2, a group represented by the
formula: --BR2, a boric acid ester residual group, a group
represented by the formula: --Si(OR)3r a sulfo group, a
hydrocarbylsulfo group optionally having a substituent, a hydrocarbyl
sulfonyl group optionally having a substituent, a sulfino group, a
hydrocarbylsulfino group optionally having a substituent, a group
represented by the formula: --NRC(═O)OR, a group represented by the
formula: --NRC(═O)SR, a group represented by the formula:
--NRC(═S)OR, a group represented by the formula: --NRC(═S)SR, a
group represented by the formula: --OC(═O)NR2, a group
represented by the formula: --SC(═O)NR2, a group represented by
the formula: --OC(═S)NR2, a group represented by the formula:
--SC(═S)NR2, a group represented by the formula:
--NRC(═O)NR2, and a group represented by the formula:
--NRC(═S)NR2.

[0164] In the groups represented by the formulae described above, R
represents a hydrogen atom, or a hydrocarbyl group optionally having a
substituent. The plurally present substituents may form a ring by bonding
with each other.

[0165] Examples of the halogen atom being a substituent that the above
described aromatic compound may have may include a fluorine atom, a
chlorine atom, a bromine atom, and an iodine atom. The fluorine atom, the
chlorine atom, and the bromine atom are preferable as the halogen atom
that the aromatic compound can have.

[0166] Examples of the hydrocarbyl group optionally having a substituent
being a substituent that the above described aromatic compound may have
may include alkyl groups having 1 to 50 carbon atoms such as a methyl
group, an ethyl group, a propyl group, an isopropyl group, a butyl group,
an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group,
a hexyl group, a nonyl group, a dodecyl group, a pentadecyl group, an
octadecyl group, and a docosyl group; cyclic saturated hydrocarbyl groups
having 3 to 50 carbon atoms such as a cyclopropyl group, a cyclobutyl
group, a cyclopentyl group, a cyclohexyl group, a cyclononyl group, a
cyclododecyl group, a norbornyl group, and an adamantyl group; alkenyl
groups having 2 to 50 carbon atoms such as an ethenyl group, a propenyl
group, a 3-butenyl group, a 2-butenyl group, a 2-pentenyl group, a
2-hexenyl group, a 2-nonenyl group, and a 2-dodecenyl group; aryl groups
having 6 to 50 carbon atoms such as a phenyl group, a 1-naphthyl group, a
2-naphthyl group, a 2-methylphenyl group, a 3-methylphenyl group, a
4-methylphenyl group, a 4-ethylphenyl group, a 4-propylphenyl group, a
4-isopropylphenyl group, a 4-butylphenyl group, a 4-tert-butylphenyl
group, a 4-hexylphenyl group, a 4-cyclohexylphenyl group, a
4-adamantylphenyl group, and 4-phenylphenyl group; and arylalkyl groups
having 7 to 50 carbon atoms such as a phenylmethyl group, a
1-phenyleneethyl group, a 2-phenylethyl group, a 1-phenyl-1-propyl group,
a 1-phenyl-2-propyl group, a 2-phenyl-2-propyl group, a 3-phenyl-1-propyl
group, a 4-phenyl-1-butyl group, a 5-phenyl-1-pentyl group, and a
6-phenyl-1-hexyl group. As the hydrocarbyl group, the alkyl groups having
1 to 50 carbon atoms and the aryl groups having 6 to 50 carbon atoms are
preferable; alkyl groups having 1 to 12 carbon atoms and aryl groups
having 6 to 18 carbon atoms are more preferable; and alkyl groups having
6 to 12 carbon atoms and aryl groups having 6 to 12 carbon atoms are
further preferable.

[0167] The hydrocarbylthio group optionally having a substituent being a
substituent that the above described aromatic compound may have is a thio
group in which a part of or all of one to three hydrogen atoms,
especially one or two hydrogen atoms, constituting the group is or are
substituted by hydrocarbyl group(s), optionally having a substituent,
which the above described aromatic compound may have (hereinafter,
referred to as the "above described hydrocarbyl group"). The
hydrocarbylthiocarbonyl group optionally having a substituent being a
substituent that the above described aromatic compound may have is a
thiocarbonyl group in which a part of or all of one to three hydrogen
atoms, especially one or two hydrogen atoms, constituting the group is or
are substituted by the above described hydrocarbyl group(s). The
hydrocarbyldithio group optionally having a substituent being a
substituent that the above described aromatic compound may have is a
dithio group in which a part of or all of one to three hydrogen atoms,
especially one or two hydrogen atoms, constituting the group is or are
substituted by the above described hydrocarbyl groups. The hydrocarbyloxy
group optionally having a substituent being a substituent that the above
described aromatic compound may have is an oxy group in which a part of
or all of one to three hydrogen atoms, especially one or two hydrogen
atoms, constituting the group is or are substituted by the above
described hydrocarbyl group(s). The hydrocarbylcarbonyl group optionally
having a substituent being a substituent that the above described
aromatic compound may have is a carbonyl group in which a part of or all
of one to three hydrogen atoms, especially one or two hydrogen atoms,
constituting the group is or are substituted by the above described
hydrocarbyl groups. The hydrocarbyloxycarbonyl group optionally having a
substituent being a substituent that the above described aromatic
compound may have is an oxycarbonyl group in which a part of or all of
one to three hydrogen atoms, especially one or two hydrogen atoms,
constituting the group is or are substituted by the above described
hydrocarbyl group(s). The hydrocarbylcarbonyloxy group optionally having
a substituent being a substituent that the above described aromatic
compound may have is a carbonyloxy group in which a part of or all of one
to three hydrogen atoms, especially one or two hydrogen atoms,
constituting the group is or are substituted by the above described
hydrocarbyl group(s).

[0168] The hydrocarbylamino group in which a hydrogen atoms in the
hydrocarbyl group is optionally substituted by a substituents and the
dihydrocarbylamino group in which a hydrogen atom in the hydrocarbyl
group may be substituted by a substituents being a substituent that the
above described aromatic compound may have are amino groups in which one
or two hydrogen(s) constituting each group is or are substituted by the
above described hydrocarbyl group(s). The hydrocarbylphosphino group
optionally having a substituent and the dihydrocarbylphosphino group
optionally having a substituent that the above described aromatic
compound may have are phosphino groups in which one or two hydrogens
constituting each group is or are substituted by the above described
hydrocarbyl group(s).

[0169] The hydrocarbylcarbamoyl group in which a hydrogen atom in the
hydrocarbyl group is optionally substituted by a substituent and the
dihydrocarbylcarbamoyl group in which a hydrogen atom in the hydrocarbyl
group is optionally substituted by a substituent being a substituent that
the above described aromatic compound may have are carbamoyl groups in
which one or two hydrogen(s) constituting each group is or are
substituted by the above described hydrocarbyl group(s).

[0170] The group represented by the formula: --BR2 and the group
represented by the formula: --Si(OR)3 being a substituent that the
above described aromatic compound may have are groups in which R is a
hydrogen atom or the above described hydrocarbyl group.

[0171] Examples of the boric acid ester residual group being a substituent
that the above described aromatic compound may have may include groups
selected from the group consisting of the group represented by the
following formulae.

##STR00021##

[0172] The hydrocarbylsulfo group optionally having a substituent being a
substituent that the above described aromatic compound may have is a
sulfo group in which one or two hydrogen atom(s) constituting the group
is or are substituted by the above described hydrocarbyl group(s). The
hydrocarbylsulfonyl group optionally having a substituent being a
substituent that the above described aromatic compound may have is a
sulfonyl group in which one or two hydrogen atom(s) constituting the
group is or are substituted by the above described hydrocarbyl group(s).
The hydrocarbylsulfino group optionally having a substituent being a
substituent that the above described aromatic compound may have is a
sulfino group in which one or two hydrogen atom(s) constituting the group
is or are substituted by the above described hydrocarbyl group(s).

[0173] The group represented by the formula: --NRC(═O)OR, the group
represented by the formula: --NRC(═O)SR, the group represented by the
formula: --NRC(═S)OR, the group represented by the formula:
--NRC(═S)SR, the group represented by the formula:
--OC(═O)NR2, the group represented by the formula:
--SC(═O)NR2, the group represented by the formula:
--OC(═S)NR2, the group represented by the formula:
--SC(═S)NR2, the group represented by the formula:
--NRC(═O)NR2, and the group represented by the formula:
--NRC(═S)NR2 being substituents that the above described
aromatic group may have are groups in which R is a hydrogen atom or the
above described hydrocarbyl group.

[0174] The monovalent heterocyclic group being a substituent that the
above described aromatic compound may have is a residual atom group in
which on hydrogen atom is eliminated from the heterocyclic compound
optionally having a substituent. Examples of the hetero ring of the
heterocyclic compound may include monocyclic heterocycles such as a
pyridine ring, a 1,2-diazine ring, a 1,3-diazine ring, a 1,4-diazine
ring, a 1,3,5-triazine ring, a furan ring, a pyrrole ring, a thiophene
ring, a pyrazole ring, an imidazole ring, an oxazole ring, a thiazole
ring, an oxadiazole ring, a thiadiazole ring, an azadiazole ring; a fused
multicyclic hetero ring in which two or more rings selected from
monocyclic aromatic rings are fused; and a crosslinkage-having
multicyclic aromatic ring having a structure in which two hetero rings,
or one hetero ring and one aromatic ring are crosslinked through a
divalent group such as a methylene group, an ethylene group and a
carbonyl group. As the hetero rings, the pyridine ring, the 1,2-diazine
ring, the 1,3-diazine ring, the 1,4-diazine ring, and the 1,3,5-triazine
ring are preferable, and the pyridine ring and the 1,3,5-triazine ring
are more preferable.

[0175] Preferable examples of the substituent that the above described
aromatic compound may have may include the halogen atom, the hydrocarbyl
group optionally having a substituent, the mercapto group, the
hydrocarbylthio group optionally having a substituent, the
hydrocarbyldithio group optionally having a substituent, the hydroxy
group, the hydrocarbyloxy group optionally having a substituent, the
carboxy group, the hydrocarbylcarbonyl group optionally having a
substituent, the amino group, a hydrocarbylamino group in which hydrogen
atom(s) in the hydrocarbyl group is or are optionally substituted by
substituent(s), the dihydrocarbylamino group in which hydrogen(s) in the
hydrocarbyl group are optionally substituted by substituent(s), the group
represented by the formula: --OP(═O)(OH)2, the sulfo group, and
the monovalent heterocyclic group; more preferable examples may include
the halogen atom, the hydrocarbyl group optionally having a substituent,
the mercapto group, the hydroxy group, the hydrocarbyloxy group
optionally having a substituent, the carboxy group, the amino group, the
group represented by the formula: --P(═O)(OH)2, the sulfo group,
and the monovalent heterocyclic group; further preferable examples may
include the hydrocarbyl group optionally having a substituent, the
mercapto group, the hydrocarbyloxy group optionally having a substituent,
the carboxy group, and a pyridyl group optionally having a substituent;
and especially preferable examples may include the hydrocarbyl group
optionally having a substituent and the hydrocarbyloxy group optionally
having a substituent.

[0176] In formula (X), a group having at least one of the ionic group and
the polar group represented by X' is the group having at least one of the
ionic group and the polar group as previously described. Definition of
the ionic group, definition of the polar group, specific examples
thereof, and preferable examples thereof are as described above.

[0177] In formula (XI), a group having at least one of the ionic group and
the polar group represented by X2 is the group having at least one
of the ionic group and the polar group as previously described.
Definition of the ionic group, definition of the polar group, specific
examples thereof, and preferable examples thereof are as described above.

[0178] In formula (X), examples of the group represented by R1 and
having a valence of (m1+1) may include a hydrocarbyl group
optionally having a substituent being a substituent that the above
described aromatic compound may have, a residual atom group in which
m1 hydrogen atom(s) are eliminated from a monovalent heterocyclic
group being a substituent that the above described aromatic compound may
have, and a group represented by the formula: --O--(R'O)m--. These
groups may form a ring. Preferable examples of the group represented by
R1 and having a valence of (m1+1) may include a residual atom
group in which m1 hydrogen atom(s) are eliminated from an alkyl
group optionally having a substituent, a residual atom group in which
m1 hydrogen atom(s) are eliminated from an aryl group optionally
having a substituent, a residual atom group in which m1 hydrogen
atom(s) are eliminated from a monovalent heterocyclic group, a residual
atom group in which m1 hydrogen atom(s) are eliminated from an alkyl
group substituted by a monovalent heterocyclic group, and a residual atom
group in which m1 hydrogen atom(s) are eliminated from an aryl group
substituted by a monovalent heterocyclic group; more preferable examples
may include a residual atom group in which m1 hydrogen atom(s) are
eliminated from an alkyl group having 1 to 6 carbon atoms, a residual
atom group in which m1 hydrogen atom(s) are eliminated from a phenyl
group, a residual atom group in which m1 hydrogen atom(s) are
eliminated from a triazinyl group, a residual atom group in which m1
hydrogen atom(s) are eliminated from an alkyl group substituted by a
triazinyl group, and a residual atom group in which m1 hydrogen
atom(s) are eliminated from an aryl group substituted by a triazinyl
group; and further preferable examples may include a residual atom group
in which m1 hydrogen atom(s) are eliminated from a hexyl group, a
residual atom group in which m1 hydrogen atom(s) are eliminated from
a phenyl group, and a residual atom group in which m1 hydrogen
atom(s) are eliminated from a phenyl group substituted by a triazinyl
group.

[0179] In formula (XI), examples of the group represented by R2 and
having a valence of (m2+1) may include a hydrocarbyl group
optionally having a substituent being a substituent that the above
described aromatic compound may have, a residual atom group in which
m2 hydrogen atom(s) are eliminated from a monovalent heterocyclic
group being a substituent that the above described aromatic compound may
have, and a group represented by the formula: --O--(R'O)m--. These
groups may form a ring. Preferable examples of the group having a valence
of (m2+1) may include a residual atom group in which m2
hydrogen atom(s) are eliminated from an alkyl group optionally having a
substituent, a residual atom group in which m2 hydrogen atom(s) are
eliminated from an aryl group optionally having a substituent, a residual
atom group in which m2 hydrogen atom(s) are eliminated from a
monovalent heterocyclic group, a residual atom group in which m2
hydrogen atom(s) are eliminated from an alkyl group substituted by a
monovalent heterocyclic group, and a residual atom group in which m2
hydrogen atom(s) are eliminated from an aryl group substituted by a
monovalent heterocyclic group; more preferable examples may include a
residual atom group in which m2 hydrogen atom(s) are eliminated from
an alkyl group having 1 to 6 carbon atoms, a residual atom group in which
m2 hydrogen atom(s) are eliminated from a phenyl group, a residual
atom group in which m2 hydrogen atom(s) are eliminated from a
triazinyl group, a residual atom group in which m2 hydrogen atom(s)
are eliminated from an alkyl group substituted by a triazinyl group, and
a residual atom group in which m2 hydrogen atom(s) are eliminated
from an aryl group substituted by a triazinyl group; and further
preferable examples may include a residual atom group in which m2
hydrogen atom(s) are eliminated from a hexyl group, a residual atom group
in which m2 hydrogen atom(s) are eliminated from a phenyl group, and
a residual atom group in which m2 hydrogen atom(s) are eliminated
from a phenyl group substituted by a triazinyl group.

[0180] In the formulae, definition, specific examples, and preferable
examples of R' and m are the same as the definition, the specific
examples, and the preferable examples of R' and m in formula (I) to
formula (IX) as described above.

[0181] A number average molecular weight, in terms of polystyrene, of the
conjugated compound used as the electron injection material in the
present invention is preferably 1×103 or more and
1×107 or less, and more preferably 1×103 or more
and 1×106 or less. In the present invention, the number
average molecular weight and a weight average molecular weight in terms
of polystyrene can be determined by using a gel permeation chromatography
(GPC).

[0182] Specific examples of the usable electron injection material for the
electron injection layer 44 of the present invention may include a
conjugated compound having a structural unit represented by following
formula (c-1) to formula (c-37), formula (d-1) to formula (d-47), formula
(e-1) to formula (e-16), formula (f-1) to formula (f-35), and formula
(g-1) to formula (g-24). In these formulae, n3 represents an integer
of 2 or more, and is preferably an integer of 2 to 30, more preferably an
integer of 2 to 20, and further preferably an integer of 6 to 10. n4
represents an integer of 1 or more, and is preferably an integer of 1 to
10, and further preferably an integer of 2 to 6. In these formulae, R
represents a hydrogen atom, or a hydrocarbyl group optionally having a
substituent. As R, an alkyl group having 1 to 6 carbon atoms is
preferable, and a methyl group, an ethyl group, a propyl group, and a
butyl group are further preferable.

[0183] In these specific examples of the electron injection material, one
or more hydrogen atoms in the structural unit may be substituted by a
substituent. Definition, specific examples, and preferable examples of
the substituent are the same as the definition, the specific examples,
and the preferable examples of the substituent represented by R3 to
R9 that the hydrocarbyl group may have.

[0185] The conjugated compound may be used by doping a dopant. One part by
weight or more and 50 parts by weight or less of the dopant with respect
to 100 parts by weight of the conjugated compound is preferably used.

[0187] The organic acid used as the dopant used in the present invention
may be a polymeric acid. Examples of the polymeric acid may include
polyvinylsulfonic acid, polystyrenesulfonic acid, sulfonated
styrene-butadiene copolymer, polyallylsulfonic acid,
polymethallylsulfonic acid, poly-2-acrylamide-2-methylpropanesulfonic
acid, and polyisoprenesulfonic acid.

[0188] Examples of the nitrile compound may include a compound having two
more cyano groups in the conjugated bond. Examples of the compound having
two or more cyano groups in the conjugated bond may include
tetracyanoethylene, tetracyanoethylene oxide, tetracyanobenzene,
tetracyanoquinodimethane, and tetracyanoazanaphthalene.

[0190] Examples of the alkali metal may include Li, Na, K, Rb, and Cs.
Examples of the alkaline earth metal may include Be, Mg, Ca, Sr, and Ba.

[0191] The electron injection layer 44 may further include an ionic
compound other than the organic compound having at least one of an ionic
group and polar group. Definition, specific examples, and preferable
examples of the ionic compound are the same as the definition, the
specific examples, and the preferable examples of the ionic compound in
the material used in the cathode as described above.

[0192] The ionic compound can be used singly or in combination of two or
more compounds. A molecular weight of the ionic compound is preferably
less than 1,000, more preferably less than 800, further preferably less
than 500, and particular preferably less than 300.

[0193] The amount of added ionic compound in the electron injection layer
44 of the light-emitting device of the present invention is usually 0.01
parts by weight or more and 1,000 parts by weight or less, preferably 0.1
parts by weight or more and 100 parts by weight or less, and more
preferably 1 part by weight or more and 50 parts by weight or less, with
respect to 100 parts by weight of the organic compound having at least
one of an ionic group and polar group.

[0194] Examples of a method for forming the electron injection layer 44
may include a vacuum evaporation method and a coating method. The coating
method is preferable as the method for forming the electron injection
layer 44. Definition, specific examples, and preferable examples of the
coating method are the same as the definition, the specific examples, and
the preferable examples of the method for forming the cathode by the
coating method as described above.

[0195] In the present invention, an aspect "the cathode 34 and the
electron injection layer 44 are adjacent (connected)" is realized by a
process of forming the electron injection layer 44 after forming the
cathode 34, and then stacking them, a process of forming the cathode 34
after forming the electron injection layer 44, and then stacking them, or
a process of mixing an electron injection material and a cathode material
to obtain an mixture, and thereafter forming a mixed layer by using the
mixture. The cathode and the electron injection layer formed by the
process described above may form a composite part in such a degree that
adjacent parts cannot be distinguished.

[0196] In the light-emitting device of the present invention, at least one
of the cathode, the anode, and the electron injection layer preferably
contains an ionic compound. More preferably, the anode or the electron
injection layer contains the ionic compound. Both of the cathode and the
electron injection layer can contains the ionic compound. More
preferably, the electron injection layer contains the ionic compound
because operation stability of the light-emitting device is improved.

[0197] --Light-Emitting Layer--

[0198] The light-emitting layer 50 of the light-emitting device 10 has a
function in which holes can be injected from the anode or the hole
injection layer to the light-emitting layer at the time of application of
an electric field, a function in which electrons can be injected from the
cathode or the electron injection layer, a function in which the injected
charge is moved by electric field force, and a function that provides a
field of recombination of the electrons and the holes and leads to
light-emitting. The light-emitting layer is a single layer constitution
made of only one layer or a stacked layer constitution made of two or
more layers. Examples of a light-emitting material may include a known
low molecular weight compound containing an organic compound, a high
molecular weight compound containing an organic compound, and a triplet
light-emitting complex containing an organic compound.

[0199] Examples of the low molecular weight compound may include dyes such
as a naphthalene derivative, anthracene and a derivative thereof,
perylene and a derivative thereof, a polymethine dye, a xanthene dye, a
coumarin dye, and cyanine dye; a metal complex of 8-hydroxyquinoline, a
metal complex of 8-hydroxyquinoline derivative, an aromatic amine,
tetraphenylcyclopentadiene and a derivative thereof, and
tetraphenylbutadiene and a derivative thereof. Specifically, known
compounds such as the compounds described in JP 57-51781 A and JP
59-194393 A can be used as the low molecular weight compound.

[0201] Examples of the triplet light-emitting complex may include
Ir(ppy)3 and Btp2Ir(acac) represented by the following formula
and having iridium (Ir) as a center metal, ADS066GE (trade name,
manufactured by American Dye Source, Inc.), PtOEP having platinum (Pt) as
a center metal, and Eu(TTA)3phen having europium (Eu) as a center
metal.

##STR00045##

[0202] An optimum value of a thickness of the light-emitting layer varies
depending on a material used. The thickness of the light-emitting layer
may be selected so that drive voltage and light-emitting efficiency are
reasonable values. The thickness of the light-emitting layer is usually 1
nm or more and 1 μm or less, preferably 2 nm or more and 500 nm or
less, more preferably 5 nm or more and 200 nm or less, and further
preferably 50 nm or more and 150 nm or less.

[0203] Examples of a method for forming the light-emitting layer 50 may
include a vacuum evaporation method and a coating method. The coating
method is preferable as the method for forming the light-emitting layer
50. Definition, specific examples, and preferable examples of the coating
method are the same as the definition, the specific examples, and the
preferable examples of the method for forming the cathode by the coating
method as described above.

[0204] --Hole Injection Layer--

[0205] In the light-emitting device 10 of the present invention, it is
possible to form the hole injection layer 42 a using a hole injection
material. The light-emitting device of the present invention may have the
hole injection layer between the light-emitting layer and the anode. The
hole injection layer is a single layer constitution made of only one
layer or a stacked layer constitution made of two or more layers.

[0206] Examples of the hole injection material may include a carbazole
derivative, a triazole derivative, an oxazole derivative, an oxadiazole
derivative, an imidazole derivative, fluorene derivative, a
polyarylalkane derivative, a pyrazoline derivative, a pyrazolone
derivative, phenylenediamine derivative, a arylamine derivative, a
star-burst-type amine, a phthalocyanine derivative, an amino-substituted
chalcone derivative, a styrylanthracene derivative, a fluorenone
derivative, a hydrazone derivative, a stilbene derivative, a silazane
derivative, an aromatic tertiary amine compound, a styrylamine compound,
an aromatic dimethylidyne compound, a porphyrin compound, a polysilane
compound, a poly(N-vinylcarbazole) derivative, an organic silane
derivative, and a polymer containing these substances; conductive metal
oxides such as vanadium oxide, tantalum oxide, tungsten oxide, molybdenum
oxide, ruthenium oxide, and aluminum oxide; conductive polymeric
materials and oligomers such as polyaniline, an aniline copolymer, a
thiophene oligomer, and polythiophene; organic conductive materials and
polymers containing thereof such as
poly(3,4-ethylenedioxythiophene)/polystyrene sulfonic acid and
polypyrrole; amorphous carbon; organic compounds having acceptor
characteristic such as a tetracyanoquinodimethane derivative including
2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, a
1,4-naphthoquinone derivative, a diphenoquinone derivative, and a
polynitro compound; and silane coupling agents such as
octadecyltrimethoxysilane.

[0207] The hole injection material may be used as a single component or a
composition made of a plurality of component. The hole injection layer
42a is a single layer structure made of only a single hole injection
material or a multi-layered structure made of a plurality of layers
constituted by an hole injection material made by the same composition or
different compositions.

[0208] An optimum value of a thickness of the hole injection layer 42a
varies depending on a material used. The thickness of the hole injection
layer 42a may be selected so that drive voltage and light-emitting
efficiency have reasonable values. The thickness of the hole injection
layer 42a is usually 1 nm or more and 1 μm or less, preferably 2 nm or
more and 500 nm or less, more preferably 5 nm or more and 200 nm or less,
and further preferably 5 nm or more and 100 nm or less.

[0209] Examples of a method for forming the hole injection layer 42a may
include a vacuum evaporation method and a coating method. The coating
method is preferable as the method for forming the hole injection layer.
Definition, specific examples, and preferable examples of the coating
method are the same as the definition, the specific examples, and the
preferable examples of the method for forming the cathode by the coating
method as described above.

[0210] --Other Layers--

[0211] The light-emitting device of the present invention may further
comprise a substrate, a hole transport layer, an electron transport
layer, an interlayer, an electron injection layer, a hole blocking layer,
an electron blocking layer, and a charge generation layer.

[0212] The hole transport layer refers to a layer having a function of
transporting holes. The electron transport layer refers to a layer having
a function of transporting electrons. The interlayer is a layer existing
between the light-emitting layer and the anode and adjacent to the
light-emitting layer, and having a role of separating the light-emitting
layer and the anode, or the light-emitting layer and the hole injection
layer or the hole transport layer. The hole blocking layer is a layer
having a function of blocking holes mainly injected from the anode, and
further having either a function of receiving electrons from the cathode
or a function of transporting electrons, if necessary. The electron
blocking layer is a layer having a function of blocking electrons mainly
injected from the cathode, and further having either a function of
receiving holes from the anode or a function of transporting holes, if
necessary. The charge generation layer refers to a layer in which holes
are injected to a layer closer to the adjacent cathode, and electrons are
injected to a layer closer to the adjacent anode.

[0213] The electron transport layer and the hole transport layer are
generically referred to as a charge transport layer. The electron
injection layer and the hole injection layer generically referred to as a
charge injection layer. The hole transport layer, the electron transport
layer, the interlayer, the electron injection layer, the hole blocking
layer, the electron blocking layer, and the charge generation layer may
be a structure made of only one layer or a structure made of two more
layers. Examples of a method for forming each of these layers may include
a vacuum evaporation method and a coating method and the coating method
is preferable. Definition, specific examples, and preferable examples of
the coating method are the same as the definition, the specific examples,
and the preferable examples of the method for forming the cathode by the
coating method as described above.

[0214] --Method for Manufacturing Light-Emitting Device--

[0215] A method for manufacturing the light-emitting device according to
the embodiments of the present invention may comprise a step for applying
a coating solution that contains a conductive material having an aspect
ratio of 1.5 or more, and thereby forming the cathode or the anode.

[0216] The light-emitting device can be manufactured by, for example,
sequentially stacking each layer. The methods for forming each of the
layers are as described above.

[0217] One embodiment of the method for manufacturing the light-emitting
device of the present invention comprises a step for forming the cathode
by a coating method. Preferably, the embodiment of the method for
manufacturing the light-emitting device of the present invention further
comprises steps for forming each of the remaining layers other than the
anode by the coating method in addition to the step for forming the
cathode by the coating method. In other words, the embodiment of the
method for manufacturing the light-emitting device of the present
invention comprises the step for forming the cathode by the coating
method and the steps for forming each of the remaining layers other than
the anode by the coating method. More preferably, the embodiment of the
method for manufacturing the light-emitting device of the present
invention further comprises a step for forming the anode by the coating
method. In other words, the embodiment of the method for manufacturing
the light-emitting device of the present invention comprises a step for
forming the anode and the cathode by the coating method, or a step for
forming all of the remaining layers in addition to the anode and the
cathode by the coating method (that is, a step for forming each of the
all layers by the coating method).

[0218] In one embodiment of the light-emitting device of the present
invention, the cathode in the light-emitting device is formed by a
coating method. In the embodiment of the light-emitting device,
preferably, each of all of the remaining layers other than the anode in
addition to the cathode is formed by the coating method. In other words,
the cathode and each of all of the remaining layers other than the anode
are formed by the coating method (that is, each of all the layers except
the anode is formed by the coating method). More preferably, in the
embodiment of the light-emitting device, the anode is further formed by
the coating method. In other words, each of the anode and the cathode is
formed by the coating method, or each of all of the other remaining
layers in addition to the anode and the cathode is formed by the coating
method (that is, each of all the layers is formed by the coating method).

[0219] --Structure of Light-Emitting Device--

[0220] The structure of the light-emitting device has a forward stacked
structure and an inverted stacked structure. The forward stacked
structure is a structure manufactured by a method for manufacturing a
structure in which electrodes and organic layers are sequentially stacked
from the anode to the cathode, and for example, a structure in which the
anode, the light-emitting layer, the electron injection layer, and the
cathode are stacked on the substrate in this order so that the anode is
located closer to the substrate.

[0221] The inverted stacked structure is a structure manufactured by a
method for manufacturing a structure in which electrodes and organic
layers are sequentially stacked from the cathode to the anode, and for
example, a structure in which the cathode, the electron injection layer,
the light-emitting layer, and the anode are stacked on the substrate in
this order so that the cathode is located closer to the substrate.

[0222] Examples of the structure of the light-emitting device of the
present invention may include structures represented by following formula
a) to formula d). Examples of the inverted stacked structure include the
structures represented by formula a) and formula b), and examples of the
forward stacked structure include the structures represented by formula
c) and formula d). The structure represented by formula c) and the
structure represented by formula d) are preferable as the examples of the
structure of the light-emitting device.

[0223] Here, the symbol "/" represents that each layers interposing the
symbol "/" are adjacently connected each other. The layers in the
parentheses each independently may not be provided. Here, the cathode and
the electron injection layer must be adjacently connected each other.

[0224] Each layer may be a layer having a plurality of functions, that is,
a layer having both its own function and functions that other layers
have.

[0225] At least one of the anode and the cathode usually has optical
transparency, and preferably the cathode has the optical transparency.

[0226] The light-emitting device may have either a top emission-type
structure in which light is emitted from an exposed surface of the
opposite side to the substrate in a thickness direction of the substrate,
or a bottom emission-type structure in which light is emitted from an
exposed surface of the substrate side.

[0227] The light-emitting device is preferably a top emission-type
structure in which the light-emitting device further provides a substrate
and the anode is connected to the substrate, and light is emitted from a
side closer to the cathode opposite to the substrate in a thickness
direction of the substrate.

[0228] When the light-emitting device is an inverted stacked structure, a
bottom emission-type structure in which a transparent substrate having
optical transparency is used as the substrate and the cathode is
connected to the transparent substrate, and light is emitted from a side
closer to the cathode (a substrate side) may be used.

[0229] In another embodiment of the light-emitting device of the present
invention, a device of both-sided light emitting-type device in which
both of the anode and the cathode have optical transparency and light is
emitted from both the side closer to the anode and the side closer to the
cathode by using a material having optical transparency for the anode and
the cathode can be manufactured.

[0230] In the both-sided light emitting-type light-emitting device, layers
other than the cathode and the anode (such as the electron injection
layer and the light-emitting layer) in the device may be opaque layers or
transparent layers. When the layers other than the cathode and the anode
are transparent, the both-sided light emitting-type device has optical
transparency when light is not emitted. However, the device is opaque at
the time of emitting light because transparency of light is prevented by
the light-emitting of the device.

[0231] --Application of Light-Emitting Device--

[0232] A display device and a lighting device can be manufactured by using
the light-emitting device of the present invention. The display device
provides the light-emitting device as one pixel unit. An array of the
pixel units can be an array usually employed for display devices such as
a television set, and can be a form of arraying a large number of pixels
on one substrate. In the display device, the pixels arrayed on the
substrate may be formed in a pixel region defined by a bank.

[0233] <Photovoltaic Cell>

[0234] With reference to FIG. 2A and FIG. 2B, a constitutional example of
a photovoltaic cell will be described.

[0236] The photovoltaic cell of an embodiment of the present invention
comprises a cathode, an anode, a charge separation layer interposed
between the cathode and the anode, and an electron injection layer
provided between the cathode and the charge separating layer and
connected to the cathode, in which at least one of the cathode and the
anode contains a conductive material having an aspect ratio of 1.5 or
more, and the electron injection layer contains an organic compound
having at least one of an ionic group and a polar group.

[0237] The cathode, the anode, and the electron injection layer of the
photovoltaic cell may further contain an ionic compound. Definition,
specific examples, and preferable examples of the ionic compound are the
same as the definition, the specific examples, and the preferable
examples of the ionic compound in the cathode of the light-emitting
device as described above.

[0238] The ionic compound can be used singly or in combination of two or
more compounds. A molecular weight of the ionic compound is preferably
less than 1,000, more preferably less than 800, further preferably less
than 500, and particular preferably less than 300.

[0239] When the cathode 34 of the photovoltaic cell contains ionic
compound, the amount of added ionic compound in the cathode is usually
0.01 parts by weight or more and 1,000 parts by weight or less,
preferably 0.1 parts by weight or more and 100 parts by weight or less,
and more preferably 1 part by weight or more and 50 parts by weight or
less, with respect to 100 parts by weight of the material of the cathode.

[0240] When the anode 32 of the photovoltaic cell of the present invention
contains the ionic compound, the amount of added ionic compound in the
anode is usually 0.01 parts by weight or more and 1,000 parts by weight
or less, preferably 0.1 parts by weight or more and 100 parts by weight
or less, and more preferably 1 part by weight or more and 50 parts by
weight or less, with respect to 100 parts by weight of the material of
the anode.

[0241] When the electron injection layer 44 of the photovoltaic cell of
the present invention contains ionic compound, the amount of added ionic
compound in the manufacturing process of the electron injection layer is
usually 0.01 parts by weight or more and 1,000 parts by weight or less,
preferably 0.1 parts by weight or more and 100 parts by weight or less,
and more preferably 1 part by weight or more and 50 parts by weight or
less, with respect to 100 parts by weight of the organic compound having
at least one of an ionic group and a polar group.

[0242] Of the cathode and the anode, at least an electrode at the side
when light is incident, that is, at least one electrode is an transparent
or semi-transparent electrode that transmits the incident light.

Constitutional Example (1)

[0243] As illustrated in FIG. 2A, the photovoltaic cell 10 of
constitutional example (1) comprises a pair of electrodes comprising the
anode 32 and cathode 34, and a charge separation layer 70 interposed
between the pair of electrodes. Namely, the photovoltaic cell 10 of
constitutional example (1) is a bulk heterojunction-type photovoltaic
cell.

[0244] A photovoltaic cell is usually formed on a substrate. Namely, the
photovoltaic cell 10 is provided on the main surface of the substrate 20.

[0245] When the substrate 20 is opaque, the cathode 34 that faces to the
anode 32 and provided at the opposite side to the substrate side (that
is, a further electrode from the substrate 20) is preferably transparent
or semi-transparent.

[0246] The charge separation layer 70 is interposed between the cathode 32
and the anode 34, and is in contact with them. The charge separation
layer 70 is an organic layer containing an electron acceptor compound and
an electron donor compound, and a layer having an essential function for
a photovoltaic function.

[0247] The anode 32 is provided on the main surface of the substrate 20.
The charge separation layer 70 is provided so as to cover the anode 32.
The electron injection layer 44 is connected to the charge separation
layer 70. The cathode 34 is connected to the electron injection layer 44.

[0248] The photovoltaic cell 10 of constitutional example (1) is
preferable because the charge separation layer 70 has a constitution of
the electron acceptor compound and the electron donor compound contained
in the single layer, and more heterojunction interfaces are comprised
therein, and as a result, photovoltaic efficiency is improved.

Constitutional Example (2)

[0249] As illustrated in FIG. 2B, the photovoltaic cell of constitutional
example (2) comprises the pair of electrodes comprising the anode 32 and
cathode 34, and the charge separation layer 70 interposed between the
pair of electrodes, the charge separation layer 70 comprising an electron
acceptor layer 74 containing the electron acceptor compound and an
electron donor layer 72 containing the electron donor compound and
connected to the electron acceptor layer 74. Namely, the photovoltaic
cell 10 of constitutional example (2) is a heterojunction-type
photovoltaic cell.

[0250] The photovoltaic cell 10 is provided on the main surface of the
substrate 20. The anode 32 is provided on the main surface of the
substrate 20.

[0251] The charge separation layer 70 is interposed between the anode 32
and the electron injection layer 44, and is in contact with them. The
charge separation layer 70 of constitutional example 2 is a layered
structure in which the electron acceptor layer 74 containing the electron
acceptor compound and the electron donor layer 72 containing the electron
donor compound are connected.

[0252] The electron donor layer 72 is provided so as to be connected to
the anode 32. The electron acceptor layer 74 is provided so as to be
connected to the electron donor layer 72. The electron injection layer 44
is connected to the electron acceptor layer 74. The cathode 34 is
connected to the electron injection layer 44.

[0253] --Charge Separation Layer--

[0254] The charge separation layer 70 may contain each of the electron
donor compound and the electron acceptor compound singly or in
combination of two more compounds. The electron donor compound or the
electron acceptor compound is relatively determined by energy level of
these compounds.

[0255] Examples of the electron donor compound may include a pyrazoline
derivative, an arylamine derivative, a stilbene derivative, a
triphenyldiamine derivative, and a conjugated macromolecular compound.
Examples of the conjugated macromolecular compound may include
oligothiophene and a derivative thereof, polyfluorene and a derivative
thereof, polyvinylcarbazole and a derivative thereof, polysilane and a
derivative thereof, a polysiloxane derivative having aromatic amines in
the main chain or the side chain thereof, polyaniline and a derivative
thereof, polypyrrole and a derivative thereof, a polyphenylenevinylene
and derivative thereof, and polythienylenevinylene and a derivative
thereof.

[0256] Examples of the electron acceptor compound may include an
oxadiazole derivative, anthraquinodimethane and a derivative thereof,
benzoquinone and a derivative thereof, naphthoquinone and a derivative
thereof, anthraquinone and a derivative thereof,
tetracyanoanthraquinodimethane and a derivative thereof, a fluorenone
derivative, diphenyldicyanoethylene and a derivative thereof, a
diphenoquinone derivative, a metal complexe of 8-hydroxyquinoline and a
derivative thereof, polyquinoline and a derivative thereof,
polyquinoxaline and a derivative thereof, polyfluorene and a derivative
thereof, fullerenes such as C60 fullerene and a derivative thereof,
phenanthrene derivatives such as bathocuproine, metal oxides such as
titanium oxide, and a carbon nanotube. As the electron acceptor
compounds, titanium oxide, the carbon nanotube, the fullerenes, and the
fullerene derivatives are preferable, and the fullerenes and the
fullerene derivatives are particularly preferable.

[0257] A thickness of the charge separation layer is preferably 1 nm or
more and 100 μm or less, more preferably 2 nm or more and 1,000 nm or
less, further preferably 5 nm or more and 500 nm or less, and
particularly preferably 20 nm or more and 200 nm or less.

[0258] The charge separation layer is formed by any methods, and examples
of a method for forming the charge separation layer may include a vacuum
evaporation method and a coating method. The coating method is preferable
as the method for forming the charge separation layer. The coating method
is the same as the method in relation to each layer constituting the
light-emitting device as described above.

[0259] --Layers Other than Charge Separation Layer--

[0260] In the photovoltaic cell 10, for example, an additional layer such
as a layer having a function of improving an injection characteristic (a
transport characteristic) of charges (electrons and holes) may be
provided between one of the electrodes of the anode 32 and the cathode 34
and the charge separation layer.

[0261] Examples of the additional layer may include the electron injection
layer and the hole injection layer (the charge injection layer), the hole
transport layer and the electron transport layer (the charge transport
layer), and the interlayer.

[0262] Similar constitution to the constitution for the light-emitting
device as previously described may be used for constitution of layers
other than the charge separation layer, that is, the cathode, the anode,
the substrate, the electron injection layer, the hole injection layer,
the hole transport layer, the electron transport layer, the interlayer,
and the like. Therefore, the detailed description of constitution of
these layers is omitted.

[0263] --Method for Manufacturing Photovoltaic Cell--

[0264] In a method for manufacturing a photovoltaic cell according to an
embodiment of the present invention comprising a cathode, an anode, a
charge separation layer interposed between the cathode and the anode, and
an electron injection layer provided between the cathode and the charge
separation layer and connected to the cathode, the method comprises the
steps of: applying a coating solution that contains an organic compound
having at least one of an ionic group and a polar group, thereby forming
the electron injection layer, and applying a coating solution that
contains the conductive material having the aspect ratio of 1.5 or more,
thereby forming the cathode connected to the electron injection layer.

[0265] The photovoltaic cell can be manufactured by, for example,
sequentially stacking each layer described above on the substrate.
Methods for forming each of the layers described above other than the
charge separation layer can be performed the same methods for forming
each of the corresponding layers of the light-emitting device. Therefore,
the detailed description of these methods is omitted.

[0266] One embodiment of the method for manufacturing the photovoltaic
cell of the present invention comprises a step for forming the cathode by
the coating method. Preferably, the embodiment of the method for
manufacturing the photovoltaic cell comprises steps for forming each of
the remaining layers other than the anode by the coating method in
addition to the step for forming the cathode by the coating method. In
other words, the embodiment of the method for manufacturing the
photovoltaic cell comprises the step for forming the cathode by a coating
method and the steps for forming each of the remaining layers other than
the anode by the coating method.

[0267] More preferably, the embodiment of the method for manufacturing the
photovoltaic cell further comprises a step for forming the anode by the
coating method. In other words, the embodiment of the method for
manufacturing the photovoltaic cell comprises steps for forming each of
the anode and the cathode by the coating method, or a step for forming
all of the remaining layers in addition to the anode and the cathode by
the coating method (that is, steps for forming each of the all layers by
the coating method).

[0268] In one embodiment of the photovoltaic cell of the present
invention, the cathode in the photovoltaic cell is formed by the coating
method. Preferably, in the embodiment of the photovoltaic cell, each of
all the remaining layers other than the anode in addition to the cathode
is formed by the coating method. In other words, the cathode and each of
all the remaining layers other than the anode are formed by the coating
method (that is, each of all the remaining layers other than the anode is
formed by the coating method). More preferably, in the embodiment of the
photovoltaic cell, the anode is further formed by the coating method. In
other words, each of the anode and the cathode is formed by the coating
method, or each of all the other remaining layers in addition to the
anode and the cathode is formed by the coating method (that is, each of
all the layers is formed by the coating method).

EXAMPLES

[0269] Hereinafter, Examples and Comparative examples will be specifically
described. However, the present invention is not limited to following
Examples.

[0270] <Analysis Methods>

[0271] A weight average molecular weight (Mw) and a number average
molecular weight (Mn) of the conjugated compound were determined by using
gel permeation chromatography (GPC) (manufactured by TOSOH CORPORATION,
Trade name: HLC-8220GPC) as the weight average molecular weight and the
number average molecular weight in terms of polystyrene. A sample for
measurement was dissolved into tetrahydrofuran so that a concentration of
the solution is about 0.5% by weight, and the 50 μL of dissolved
sample was injected into the GPC. As a mobile phase of the GPC,
tetrahydrofuran was used and flowed at a flow rate of 0.5 mL/min. A
detection wavelength was set to 254 nm.

[0272] Structural analysis of the conjugated compounds was performed by
1H-NMR analysis using a 300 MHz NMR spectrometer (manufactured by
Varian, Inc.). 1H-NMR analysis was performed by using a sample
dissolved into a deuteration solvent that can dissolve the sample so as
to be a concentration of 20 mg/mL.

Synthesis Example 1

Synthesis of Silver Nano-Structure A

[0273] A flask having a volume of 50 mL and containing 5 mL of ethylene
glycol was immerged into an oil bath having a temperature of 150°
C. The ethylene glycol was pre-heated for 60 minutes with bubbling air.
After the pre-heating, gas for the bubbling was changed from air to
nitrogen gas to replace the atmosphere in the flask by nitrogen gas, and
then the bubbling was stopped. Subsequently, 1.5 mL of 0.1 M silver
nitrate-ethylene glycol solution, 1.5 mL of 0.15 mol/L
polyvinylpyrrolidone (hereinafter, also referred to as "PVP",
manufactured by Sigma-Aldrich Co. LLC., a weight average molecular weight
described in the brochure: 5.5×104) ethylene glycol solution,
and 40 μL of 4 mmol/L copper chloride dihydrate ethylene glycol
solution were further added and the mixture was stirred for 120 minutes,
thus obtaining a dispersion liquid of a silver nano-structure. After
cooling the obtained dispersion liquid to 40° C., the dispersion
liquid was centrifuged to obtain a precipitate. The obtained precipitate
was dried, thus obtaining the silver nano-structure (hereinafter,
referred to as the "silver nano-structure A").

[0274] A photograph of the obtained silver nano-structure A taken by a
scanning electron microscope (manufactured by JEOL Ltd., trade mane:
JSM-5500) (hereinafter, referred to as "SEM") was visually observed. The
silver nano-structure A is wire-shaped, an average value of the shortest
diameter of about 30 nm, and an average value of the longest diameter of
about 15 μm. An average value of an aspect ratio of at least 10
particles of silver nano-structure A determined by the SEM was about 500.

Synthesis Example 2

Synthesis of Conjugated Compound P-1

[0275] 52.5 g (0.16 mol) of 2,7-dibromo-9-fluorenone, 154.8 g (0.93 mol)
of ethyl salicylate, and 1.4 g (0.016 mol) of mercaptoacetic acid were
placed into a flask having a volume of 3,000 mL, and the atmosphere in
the flask was replaced by nitrogen gas. Methanesulfonic acid (630 mL) was
further added into the flask and the mixture was stirred overnight at
75° C. The mixture was allowed to cool. When the mixture was added
to ice water and the resultant mixture was stirred for 1 hour, a solid
was generated. The generated solid was separated by filtration and the
solid was washed with heated acetonitrile. The washed solid was dissolved
into acetone. A solid was obtained by recrystallization from the obtained
acetone solution and separated by filtration. The obtained solid (62.7
g), 2-[2-(2-methoxyethoxy)ethoxy]ethoxy-p-toluenesulfonate (86.3 g, 0.27
mmol), potassium carbonate (62.6 g, 0.45 mmol), and 18-crown-6 (7.2 g,
0.027 mol) were dissolved into N,N-dimethylformamide (DMF) (670 mL). The
obtained solution was transferred to a flask and stirred overnight at
105° C. The obtained solution was allowed to cool to the room
temperature. The mixture is added to ice water, and the resultant mixture
was stirred for 1 hour. Chloroform was added the solution to perform
liquid separation and extraction.
2,7-dibromo-9,9-bis[3-ethoxycarbonyl-4-[2-[2-(2-methoxyethoxy)ethoxy]etho-
xy]phenyl-fluorene (compound B) (51.2 g) was obtained by concentrating the
obtained solution. The yield was 31%.

[0277] 810 mg (3.0 mmol) of bis(1,5-cyclooctadiene) nickel, 469 mg (3.0
mmol) of 2,2'-bipyridyl, 325 mg (3.0 mmol) of 1,5-cyclooctadiene, and a
mixed solvent of 10 mL of toluene and 10 mL of N,N-dimethylformamide were
placed in a flack having a volume of 100 mL whose inner gas was replaced
by argon gas, and the mixture was dissolved. A solution in which 850 mg
(0.90 mmol) of the compound B and 48 mg (0.10 mmol) of the compound C
were dissolved into a mixed solvent of 5 mL of toluene and 15 mL of
dimethylformamide was further added into the flask. After stirring the
reaction solution for 6 hours at 80° C., 16 mg (0.10 mmol) of
bromobenzene was added, and the mixture was further stirred for 1 hour at
80° C. After cooling the obtained reaction solution to the room
temperature, the obtained reaction solution was added dropwise to 300 mL
of methanol. When the mixture was stirred for 1 hour, a solid was
deposited. The solid was filtrated, and the residue was washed with
hydrochloric acid, distilled water, aqueous ammonia, and distilled water
in this order, and dried, thus obtaining 596 mg of the conjugated
compound P-1. The yield was 81%.

[0278] From the result of NMR analysis, the conjugated compound P-1
contains two structural units represented by the following formulae in a
molar ratio of 9:1 (a theoretical value from the amount of fed raw
materials) in the order of description.

##STR00048##

[0279] A number average molecular weight of the conjugated compound P-1 in
terms of polystyrene was 2.0×104.

Synthesis Example 3

Synthesis of Conjugated Compound P-2

[0280] The conjugated compound P-1 (100 mg) was fed into a flask whose
inner gas was replaced by argon gas, and was dissolved into 20 mL of
tetrahydrofuran and 2 mL of ethanol. 3 mL of aqueous solution containing
334 mg of cesium hydroxide was added to the obtained solution and the
resultant solution was stirred for 2 hours at 55° C. 5 mL of
methanol was added to the obtained reaction solution, and the resultant
solution was stirred with heating for 3 hours at 60° C.
Subsequently, 3 mL of aqueous solution containing 334 mg of cesium
hydroxide was added to the reaction solution, and the resultant solution
was refluxed by heating for 2 hours at 65° C. When the solvent of
the obtained reaction solution was removed by distillation, a solid was
deposited. The solid was washed with water. The solid after washing was
filtrated and the residue was dried, thus obtaining a 110 mg of
conjugated compound containing two structural units represented by the
following formulae in a molar ratio of 9:1 (a theoretical value from the
amount of fed raw materials) in the order of description (hereinafter,
referred to as "conjugated compound P-2") was obtained.

##STR00049##

[0281] The yield was 88%. It was confirmed by NMR spectrum that a signal
based on an ethyl group of an ethyl ester part in the conjugated compound
P-1 was completely disappeared.

Synthesis Example 4

Synthesis of Conjugated Compound P-3

[0282] The compound B (15 g), bis(pinacolato)diboron (8.9 g),
[1,1'-bis(diphenylphosphino)ferrocene]dichloropalladium (II)
dichloromethane complex (0.8 g), 1,1'-bis(diphenylphosphino)ferrocene
(0.5 g), potassium acetate (9.4 g), and dioxane (400 mL) were added into
a flack having a volume of 1,000 mL whose inner gas was replaced by argon
gas, and mixed. The mixture was heated at 110° C., and refluxed by
heating for 10 hours. After allowing to cool, the reaction solution was
filtrated and the filtrate was concentrated under reduced pressure. The
reaction mixture was washed three times with methanol. The precipitate
was dissolved in toluene, and activated carbon was added to the solution
and the resultant mixture was stirred. Thereafter, the obtained mixture
was filtrated and the filtrate was concentrated under reduced pressure,
thus obtaining
2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolane-2-yl)-9,9-bis[3-ethoxycar-
bonyl-4-[2-[2-(2-methoxyethoxy)ethoxy]ethoxy]phenyl]-fluorene (compound D)
(11.7 g) represented by the following formula was obtained.

##STR00050##

[0283] The compound B (0.55 g), the compound D (0.61 g),
tetrakistriphenylphosphine palladium (0.01 g), methyltrioctyl ammonium
chloride (manufactured by Aldrich Co. LLC., trade name: Aliquat 336
(registered trademark)) (0.20 g), and toluene (10 mL) were added into a
flask having a volume of 100 mL whose inner gas was replaced by argon
gas, and mixed. The mixture was heated at 105° C. 2M sodium
carbonate aqueous solution (6 mL) was added dropwise to the reaction
solution, and the resultant solution was refluxed for 8 hours.
4-tert-butylphenylboronic acid (0.01 g) was added to the reaction
solution and the resultant solution was refluxed for 6 hours.
Subsequently, sodium diethyldithiocarbamate aqueous solution (10 mL,
concentration: 0.05 g/mL) was added, and the resultant solution was
stirred for 2 hours. The obtained solution was added dropwise to 300 mL
of methanol and the obtained mixture was stirred for 1 hour. The
deposited precipitate was filtered, dried for 2 hours under reduced
pressure, and dissolved in 20 mL of tetrahydrofuran. The obtained
solution was added dropwise to a mixed solvent of 120 mL of methanol and
50 mL of acetic acid aqueous solution (3% by weight) and the resultant
solution was stirred for 1 hour, and thereafter, the deposited
precipitate was filtered. The obtained precipitate was dissolved in 20 mL
of tetrahydrofuran. The obtained solution was added dropwise to 200 mL of
methanol and the resultant solution was stirred for 30 minutes, and
thereafter, the deposited precipitate was filtered to obtain a solid. The
obtained solid was dissolved in tetrahydrofuran to obtain a
tetrahydrofuran solution. The tetrahydrofuran solution was purified by
passing through an alumina column and a silica gel column. The
tetrahydrofuran solution recovered from the column was concentrated, and
thereafter, the concentrated solution was added dropwise to methanol. A
deposited solid was filtrated and the residue was dried, thus obtaining
520 mg of a conjugated compound (hereinafter, referred to as the
"conjugated compound P-3").

[0284] From the result of NMR measurement, the conjugated compound P-3 has
a structural unit represented by the following formula.

##STR00051##

[0285] A number average molecular weight of the conjugated compound P-3 in
terms of polystyrene was 5.2×104.

Synthesis Example 5

Synthesis of Conjugated Compound P-4

[0286] The conjugated compound P-3 (200 mg) was added into a flask having
a volume of 100 mL, and the gas in the flask was replaced by nitrogen
gas. Tetrahydrofuran (20 mL) and ethanol (20 mL) were added and the
mixture was heated to 55° C. An aqueous solution made by
dissolving cesium hydroxide (200 mg) in water (2 mL) was added to the
mixture and the resultant mixture was stirred for 6 hours at 55°
C. The mixture was cooled to the room temperature, and thereafter, the
reaction solvent was removed by distillation under reduced pressure. The
generated solid was washed with water, and dried under reduced pressure,
thus obtaining 150 mg of a conjugated compound having a structural unit
represented by the following formula (hereinafter, referred to as
"conjugated compound P-4").

##STR00052##

[0287] It was confirmed by NMR spectrum in which a signal based on an
ethyl group of an ethyl ester part in the conjugated compound P-3
completely disappeared.

Synthesis Example 6

Synthesis of Hole Transport Material A

[0288] In a three-necked round bottom flask having a volume of 1 L and
equipped with a reflux condenser and an overhead stirrer,
2,7-bis(1,3,2-dioxyborole)-9,9-di(1-octyl)fluorene (3.863 g, 7.283 mmol),
N,N-di(p-bromophenyl)-N-(4-(butane-2-yl)phenyl)amine (3.177 g, 6.919
mmol), and di(4-bromophenyl)benzocyclobutane amine (156.3 mg, 0.364 mmol)
were added. Subsequently, methyltrioctyl ammonium chloride (manufactured
by Aldrich Co. LLC., trade name: Aliquat 336 (registered trademark))
(2.29 g), and 50 mL of toluene were added in this order.
PdCl2(PPh3)2 catalyst (4.9 mg) was added, and thereafter,
the obtained mixture was stirred for 15 minutes in an oil bath having a
temperature of 105° C. Sodium carbonate aqueous solution (2.0M, 14
mL) was added to the mixture to obtain a reactant. The reactant was
stirred for 16.5 hours in an oil bath having a temperature of 105°
C. Subsequently, phenylboronic acid (0.5 g) was added and the resultant
reactant was stirred for 7 hours.

[0289] A water layer was removed from the reactant and an organic layer
was washed with water. The organic layer was returned to the flask, and
0.75 g of sodium diethyldithiocarbamate and 50 mL of water were added
into the flask. The reaction solution was stirred for 16 hours in an oil
bath having a temperature of 85° C. to obtain a reaction solution.
A water layer was removed from the reaction solution and an organic layer
was washed three times with water. Thereafter, the organic layer was
passed through a column packed with silica gel and basic alumina. An
operation to generate precipitate from the obtained toluene solution in
methanol was repeated two times. The obtained precipitate was dried at
60° C. under vacuum, thus obtaining 4.2 g of a macromolecular
compound being a hole transport material A. A number average molecular
weight of the hole transport material A in terms of polystyrene was
4.4×104.

Synthesis Example 7

Synthesis of Hole Transport Material B

[0290] Under inert gas atmosphere, 2,7-dibromo-9,9-di(octyl)fluorene (1.4
g, 2.5 mmol),
2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9,9-di(octyl)fluoren-
e (6.4 g, 10.0 mmol),
N,N-bis(4-bromophenyl)-N',N'-bis(4-butylphenyl)-1,4-phenylenediamine (4.1
g, 6 mmol), bis(4-bromophenyl)benzocyclobutene amine (0.6 g, 1.5 mmol),
tetraethylammonium hydroxide (1.7 g, 2.3 mmol), palladium acetate (4.5
mg, 0.02 mmol), tri(2-methoxyphenyl)phosphine (0.03 g, 0.08 mmol), and
toluene (100 mL) were mixed, and the mixture was stirred for 2 hours with
heating at 100° C. Subsequently, phenylboronic acid (0.06 g, 0.5
mmol) was added and the obtained mixture was stirred for 10 hours. After
allowing to cool the mixture, a water layer was removed, and sodium
diethyldithiocarbamate aqueous solution was added. After stirring the
mixture, an aqueous layer was removed, and an organic layer was washed
with water and further washed with acetic acid aqueous solution (3% by
weight). When the organic layer wad poured into methanol, precipitate was
generated. The precipitate was filtrated, and the residue was dissolved
again in toluene. Thereafter, the solution was passed through a silica
gel column and an alumina column. The eluted toluene solution was
recovered. When the recovered eluted toluene solution was poured into
methanol, precipitate was generated. After filtrating the precipitate,
the precipitate was dried at 50° C. under vacuum, thus obtaining a
macromolecular compound being a hole transport material (12.1 g).
According to gel permeation chromatography measurement, a weight average
molecular weight of the obtained hole transport material in terms of
polystyrene was 3.0×105, and a molecular weight distribution
index (Mw/Mn) was 3.1.

[0291] The hole transport material B is a copolymer having a structural
unit represented by the following formula:

##STR00053##

[0292] a structural unit represented by the following
formula:

[0292] ##STR00054##

[0293] and a structural unit represented by the
following formula:

[0293] ##STR00055##

[0294] in a molar ratio of 62.5:30:7.5 (a
theoretical value from the amount of fed raw materials) in the order of
description.

Synthesis Example 8

Synthesis of Light-Emitting Material B

[0295] Under innert gas atmosphere, 2,7-dibromo-9,9-di(octyl)fluorene (9.0
g, 16.4 mmol),
N,N'-bis(4-bromophenyl)-N,N'-bis(4-tert-butyl-2,6-dimethylphenyl)1,4-phen-
ylenediamine (1.3 g, 1.8 mmol),
2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9,9-di(4-hexylphenyl-
)fluorene (13.4 g, 18.0 mmol), tetraethylammonium hydroxide (43.0 g, 58.3
mmol), palladium acetate (8 mg, 0.04 mmol), tri(2-methoxyphenyl)phosphine
(0.05 g, 0.1 mmol), and toluene (200 mL) were mixed, and the mixture was
stirred for 8 hours with heating at 90° C. Subsequently,
phenylboronic acid (0.22 g, 1.8 mmol) was added and the obtained mixture
was stirred for 14 hours. After allowing to cool the mixture, a water
layer was removed, and sodium diethyldithiocarbamate aqueous solution was
added. After stirring the mixture, an aqueous layer was removed, and an
organic layer was washed with water and further washed with acetic acid
aqueous solution (3% by weight). When the organic layer was poured into
methanol, precipitate was generated. The precipitate was filtrated, and
the residue was dissolved again in toluene. Thereafter, when the solution
was passed through a silica gel column and an alumina column, precipitate
was generated. The eluted toluene solution containing the precipitate was
recovered. When the recovered eluted toluene solution was poured into
methanol, precipitate was generated. The precipitate was dried at
50° C. under vacuum, thus obtaining a macromolecular compound
being the light-emitting material (12.5 g). According to gel permeation
chromatography, a weight average molecular weight of the obtained
light-emitting material in terms of polystyrene was 3.1×105,
and a molecular weight distribution index (Mw/Mn) was 2.9.

[0296] The light-emitting material B is a copolymer having a structural
unit represented by the following formula:

##STR00056##

[0297] a structural unit represented by the following
formula:

[0297] ##STR00057##

[0298] and a structural unit represented by the
following formula:

[0298] ##STR00058##

[0299] in a molar ratio of 50:45:5 (a theoretical
value from the amount of fed raw materials) in the order of description.

Example 1

Manufacture of Light-Emitting Device k-1

[0300] On an ITO film that is formed on the glass substrate as an anode,
0.5 mL of poly(3,4-ethylenedioxythiophene)/polystyrene sulfonic acid
(manufactured by H.C. Starck GmbH, PEDOT:PSS solution, trade name:
CLEVIOS (registered trademark) P VP AI 4083) being a hole injection
material solution was applied, and then a film was made so as to be a
thickness of 70 nm by a spin coating method. The obtained glass substrate
was heated in the air for 10 minutes at 200° C., and thereafter,
the glass substrate was allowed to naturally cool to the room
temperature, thus obtaining a glass substrate A over which a hole
injection layer was formed.

[0301] 5.2 mg of the hole transport material A obtained in synthesis
example 6 and 1 mL of xylene were mixed to prepare a composition for the
hole transport layer containing 0.6% by weight of the hole transport
material A.

[0302] The composition for the hole transport layer was applied by the
spin coating method onto the glass substrate A over which the hole
injection layer was formed, thus forming a coating film having a
thickness of 25 nm. The glass substrate over which the coating film was
formed was heated under nitrogen atmosphere for 20 minutes at 200°
C. to insolubilize the coating film, and thereafter, the glass substrate
was allowed to naturally cool to the room temperature, thus obtaining a
glass substrate B over which a hole transport layer was formed.

[0303] A light-emitting material A (manufactured by Sumation Co., Ltd.,
trade name: BP 361) (11.3 mg) and 1 mL of xylene were mixed to prepare a
composition for the light-emitting layer containing 1.3% by weight of the
light-emitting material.

[0304] The composition for the light-emitting layer was applied by the
spin coating method onto the glass substrate B over which the hole
transport layer was formed, thus forming a coating film having a
thickness of 80 nm. The substrate over which the coating film was formed
was heated under nitrogen atmosphere for 15 minutes at 130° C. to
evaporate the solvent, and thereafter, the substrate was allowed to
naturally cool to the room temperature, thus obtaining a glass substrate
C over which a light-emitting layer was formed.

[0305] The conjugated compound P-4 (2.0 mg) obtained in synthesis example
5 and 1 mL of methanol was mixed to prepare a composition for the
electron injection layer containing 0.2% by weight of the conjugated
compound P-4.

[0306] The composition for the electron injection layer was applied by the
spin coating method onto the glass substrate C over which the
light-emitting layer was formed, thus forming a coating film having a
thickness of 10 nm. The substrate over which the coating film was formed
was heated under nitrogen atmosphere for 10 minutes at 130° C. to
evaporate the solvent, and thereafter, the substrate was allowed to
naturally cool to the room temperature, thus obtaining a glass substrate
D over which an electron injection layer was formed.

[0307] The silver nano-structure A (10.0 mg) and 1.3 mL of methanol was
mixed and stirred for 1 hour to prepare a composition for the cathode.

[0308] The composition for the cathode was applied by a casting method
onto the glass substrate D over which the electron injection layer was
formed, thus forming a coating film having a thickness of 200 nm. The
substrate over which the coating film was formed was heated under
nitrogen atmosphere for 10 minutes at 130° C. to evaporate the
solvent, and thereafter, the substrate was allowed to naturally cool to
the room temperature, thus obtaining a glass substrate E over which the
cathode was formed.

[0309] Finally, the glass substrate E over which the cathode was formed
was sealed under nitrogen atmosphere by using a sealing glass and a
two-liquid mixing-type epoxy resin (Robnor resins Ltd., trade name:
PX681C/NC) to prepare a light-emitting device (hereinafter, referred to
as a "light-emitting device k-1").

[0310] A forward direction voltage of 14 V was applied to the
light-emitting device k-1, and light-emitting brightness of emitted light
from a side closer to the anode in a thickness direction of the glass
substrate was measured. The light-emitting brightness was 113 cd/m2.

[0311] The light-emitting device k-1 emits light also from a side closer
to the cathode, because the light-emitting device k-1 is a both-sided
light-emitting device. Whole light-emitting brightness of the
light-emitting device k-1 in total of light-emitting brightness from the
side closer to the anode and the side closer to the cathode was almost
two times the value described above.

Example 2

Manufacture of Light-Emitting Device k-2

[0312] 5.2 mg of the hole transport material B obtained in synthesis
example 7 and 1 mL of xylene were mixed to prepare a composition for the
hole transport layer containing 0.6% by weight of the hole transport
material B.

[0313] The composition for the hole transport layer was applied by the
spin coating method onto the glass substrate A over which the hole
injection layer was formed, thus forming a coating film having a
thickness of 33 nm. The glass substrate over which the coating film was
formed was heated under nitrogen atmosphere for 20 minutes at 200°
C. to insolubilize the coating film, and thereafter, the glass substrate
was allowed to naturally cool to the room temperature, thus obtaining a
glass substrate F over which a hole transport layer was formed.

[0314] The light-emitting material B (11.3 mg) obtained in synthesis
example 8 and 1 mL of xylene were mixed to prepare a composition for the
light-emitting layer containing 1.3% by weight of the light-emitting
material B.

[0315] The composition for the light-emitting layer was applied by the
spin coating method onto the glass substrate F over which the hole
transport layer was formed, thus forming a coating film having a
thickness of 99 nm. The substrate over which the coating film was formed
was heated under nitrogen atmosphere for 15 minutes at 130° C. to
evaporate the solvent, and thereafter, the substrate was allowed to
naturally cool to the room temperature, thus obtaining a glass substrate
G over which a light-emitting layer was formed.

[0316] The conjugated compound P-4 (2.0 mg) obtained in synthesis example
5 and 1 mL of methanol were mixed to prepare a composition for the
electron injection layer containing 0.2% by weight of the conjugated
compound P-4.

[0317] The composition for the electron injection layer was applied by the
spin coating method onto the glass substrate G over which the
light-emitting layer was formed, thus forming a coating film having a
thickness of 10 nm. The substrate over which the coating film was formed
was heated under nitrogen atmosphere for 10 minutes at 130° C. to
evaporate the solvent, and thereafter, the substrate was allowed to
naturally cool to the room temperature, thus obtaining a glass substrate
H over which an electron injection layer was formed.

[0318] The silver nano-structure A (10.0 mg) and 1.3 mL of water was mixed
and stirred for 1 hour to prepare a composition for the cathode.

[0319] The composition for the cathode was applied by a casting method
onto the glass substrate H over which the electron injection layer was
formed, thus forming a coating film having a thickness of 200 nm. The
substrate over which the coating film was formed was heated under
nitrogen atmosphere for 10 minutes at 130° C. to evaporate the
solvent, and thereafter, the substrate was allowed to naturally cool to
the room temperature, thus obtaining a glass substrate I over which a
cathode was formed.

[0320] Finally, the glass substrate I over which the cathode was formed
was sealed under nitrogen atmosphere by using the sealing glass and the
two-liquid mixing-type epoxy resin (Robnor resins Ltd., trade name:
PX681C/NC) to prepare a light-emitting device (hereinafter, referred to
as a "light-emitting device k-2").

[0321] A forward direction voltage of 14 V was applied to the
light-emitting device k-2, and light-emitting brightness of emitted light
from a side closer to the anode in a thickness direction of the glass
substrate was measured. The light-emitting brightness was 1.8 cd/m2.

[0322] The light-emitting device k-2 emits light also from a side closer
to the cathode, because the light-emitting device k-2 is a both-sided
light-emitting device. Whole light-emitting brightness of the
light-emitting device k-2 in total of light-emitting brightness from the
side closer to the anode and the side closer to the cathode was almost
twice the value described above.

Example 3

Manufacture of Light-Emitting Device k-3

[0323] A light-emitting device was prepared in a similar way to Example 2
except that a composition for the electron injection layer made by mixing
the conjugated compound P-4 (2.0 mg), cesium hydroxide monohydrate (0.68
mg), and 1 mL of methanol was used instead of the composition for the
electron injection layer containing 0.2% by weight of the conjugated
compound P-4 made by mixing the conjugated compound P-4 (2.0 mg) and 1 mL
of methanol (hereinafter, referred to as a "light-emitting device k-3").

[0324] A forward direction voltage of 14 V was applied to the
light-emitting device k-3 to which a forward direction voltage of 14 V
was applied, and light-emitting brightness of emitted light from a side
closer to the anode in a thickness direction of the glass substrate was
measured. As a result, the light-emitting brightness was 21 cd/m2.
The light-emitting device k-3 emits light also from a side closer to the
cathode, because the light-emitting device k-3 is a both-sided
light-emitting device. Whole light-emitting brightness of the
light-emitting device k-3 in total of light-emitting brightness from the
side closer to the anode and the side closer to the cathode was almost
twice the value described above.

Comparative Example 1

Manufacture of Light-Emitting Device k-4

[0325] A light-emitting device was prepared in a similar way to Example 2
except that the electron injection layer was not formed (hereinafter,
referred to a "light-emitting device k-4"). Although a forward direction
voltage of 14 V was applied to the light-emitting device k-4, the
light-emitting device k-4 did not emit light.

Example 4

Manufacture of Light-Emitting Device k-5

[0326] A glass substrate on which an ITO film was formed was inserted into
a small-scale vacuum evaporation apparatus (trade name: VPC-260F,
manufactured by ULVAC KIKO, Inc.), and an aluminum film is formed onto
the ITO film by a vacuum evaporation method so that a thickness of the
aluminum film is 100 nm. Thereby, a glass substrate A' over which a
cathode was formed was obtained.

[0327] The conjugated compound P-2 and methanol was mixed to prepare a
composition for the electron injection layer so that a concentration of
the conjugated compound P-2 is 0.25% by weight.

[0328] The obtained composition for the electron injection layer was
applied by the spin coating method onto the cathode over the glass
substrate A', thus forming a coating film having a thickness of 10 nm.
The substrate over which the coating film was formed was heated under
nitrogen atmosphere for 15 minutes at 130° C. to evaporate the
solvent, and thereafter, the substrate was allowed to naturally cool to
the room temperature, thus obtaining a glass substrate B' over which an
electron injection layer was formed.

[0329] The light-emitting material (manufactured by Sumation Co., Ltd.,
trade name: BP 361) and xylene were mixed to prepare a composition for
the light-emitting layer containing 1.3% by weight of the light-emitting
material.

[0330] The composition for the light-emitting layer was applied by the
spin coating method onto the glass substrate B' over which the electron
injection layer was formed, thus forming a coating film having a
thickness of 80 nm. The substrate over which the coating film was formed
was heated under nitrogen atmosphere for 15 minutes at 130° C. to
evaporate the solvent, and thereafter, the substrate was allowed to
naturally cool to the room temperature, thus obtaining a glass substrate
C' over which a light-emitting layer was formed.

[0331] The silver nano-structure A (10 mg), 0.5 g of methanol, and 1.0 g
of poly(3,4-ethylenedioxythiophene)/polystyrene sulfonic acid
(manufactured by H. C. Starck GmbH, PEDOT:PSS solution, trade name:
CLEVIOS (registered trademark) P VP Al 4083) were mixed to prepare a
composition for a mixed layer j-1 that contains the anode and the hole
injection material and that contains 0.67% by weight of the silver
nano-structure A.

[0332] The composition for the mixed layer j-1 was applied by a casting
method onto the glass substrate C' over which the light-emitting layer
was formed, thus forming a coating film having a thickness of 1 μm.
The substrate over which the coating film was formed was heated under
nitrogen atmosphere for 15 minutes at 130° C. to evaporate the
solvent, and thereafter, the substrate was allowed to naturally cool to
the room temperature, thus obtaining a glass substrate D' over which a
mixed layer comprising the hole injection layer and the anode was formed.

[0333] The silver nano-structure A (10 mg) and 0.5 g of methanol was mixed
to prepare a composition for the anode j-2 that contains 2.0% by weight
of the silver nano-structure A.

[0334] The composition for the anode j-2 was applied by a casting method
onto the glass substrate D' over which the mixed layer comprising the
hole injection layer and the anode was formed, thus forming a coating
film having a thickness of 1 μm. The substrate over which the coating
film was formed was heated under nitrogen atmosphere for 15 minutes at
130° C. to evaporate the solvent, and thereafter, the substrate
was allowed to naturally cool to the room temperature, thus obtaining a
glass substrate E' over which an anode was formed.

[0335] The glass substrate E' over which the anode was formed was sealed
under nitrogen atmosphere by using the sealing glass and the two-liquid
mixing-type epoxy resin (Robnor resins Ltd., trade name: PX681C/NC) to
prepare a light-emitting device k-5.

[0336] A forward direction voltage of 12 V was applied to the
light-emitting device k-5, and light-emitting brightness was measured.
The light-emitting brightness was 89 cd/m2. The light-emitting
device k-5 is a top emission type light-emitting device having an
inverted stacked structure prepared by the coating method.

Example 5

Manufacture of Light-Emitting Device k-6

[0337] A light-emitting device k-6 was prepared in the same way to Example
1 except that the composition for the anode j-2 was used instead of the
composition for the mixed layer j-1 that contains the anode and the hole
injection material, and a composition for a mixed layer j-3 that is
prepared by mixing the silver nano-structure A (10 mg), 0.5 g of
methanol, and 0.5 g of poly(3,4-ethylenedioxythiophene)/polystyrene
sulfonic acid (manufactured by H. C. Starck GmbH, PEDOT:PSS solution,
trade name: CLEVIOS (registered trademark) P VP Al 4083) containing 1.0%
by weight of the silver nano-structure A containing an anode and a hole
injection material was used instead of the composition for the anode j-2
in Example 4.

[0338] A forward direction voltage of 18 V was applied to the
light-emitting device k-6, and light-emitting brightness was measured.
The light-emitting brightness was 5.4 cd/m2. The light-emitting
device k-6 is a top emission type light-emitting device having an
inverted stacked structure prepared by the coating method.

Example 6

Manufacture of Light-Emitting Device k-7

[0339] The silver nano-structure A (10 mg) and 0.5 g of methanol were
mixed to prepare the composition for the anode j-2 that contains 2.0% by
weight of the silver nano-structure A.

[0340] The composition for the anode j-2 was applied by the spin coating
method onto the glass substrate on which the ITO film was formed, thus
forming a coating film having a thickness of 100 nm. The substrate over
which the coating film was formed was heated under nitrogen atmosphere
for 15 minutes at 130° C. to evaporate the solvent, and
thereafter, the substrate was allowed to naturally cool to the room
temperature, thus obtaining a glass substrate F' over which an anode was
formed.

[0341] Poly(3,4-ethylenedioxythiophene)/polystyrene sulfonic acid
(manufactured by H. C. Starck GmbH, PEDOT:PSS solution, trade name:
CLEVIOS (registered trademark) P VP Al 4083) as the hole injection
material was applied by the spin coating method onto the anode of the
glass substrate F' over which the anode was formed, thus forming a
coating film having a thickness of 120 nm. The substrate over which the
coating film was formed was heated under nitrogen atmosphere for 10
minutes at 200° C., and thereafter, the substrate was allowed to
naturally cool to the room temperature, thus obtaining a glass substrate
G' over which a hole injection layer was formed.

[0342] 5.2 mg of the hole transport material B and 1 mL of xylene were
mixed to prepare the composition for the hole transport layer containing
0.6% by weight of the hole transport material B.

[0343] The composition for the hole transport layer was applied by the
spin coating method onto the glass substrate G' on which the hole
injection layer was formed, thus forming a coating film having a
thickness of 33 nm. The glass substrate on which the coating film was
formed was heated under nitrogen atmosphere for 20 minutes at 200°
C. to insolubilize the coating film, and thereafter, the glass substrate
was allowed to naturally cool to the room temperature, thus obtaining a
glass substrate H' over which a hole transport layer was formed.

[0344] The light-emitting material and xylene were mixed to prepare a
composition for the light-emitting layer containing 1.3% by weight of the
light-emitting material B.

[0345] The composition for light-emitting layer was applied by the spin
coating method onto the glass substrate H' over which the hole transport
layer was formed, thus forming a coating film having a thickness of 99
nm. The substrate over which the coating film was formed was heated under
nitrogen atmosphere for 15 minutes at 130° C. to evaporate the
solvent, and thereafter, the substrate was allowed to naturally cool to
the room temperature, thus obtaining a glass substrate I' over which a
light-emitting layer was formed.

[0346] The conjugated compound P-4 and methanol were mixed to prepare a
composition for the electron injection layer containing 0.2% by weight of
the conjugated compound P-4.

[0347] The obtained composition for the electron injection layer was
applied by the spin coating method onto the light-emitting layer over the
glass substrate I', thus forming a coating film having a thickness of 10
nm. The substrate over which the coating film was formed was heated under
nitrogen atmosphere for 15 minutes at 130° C. to evaporate the
solvent, and thereafter, the substrate was allowed to naturally cool to
the room temperature, thus obtaining a glass substrate J' over which an
electron injection layer was formed.

[0348] A glass substrate J' on which the electron injection layer was
formed was inserted into a small-scale vacuum evaporation apparatus
(trade name: VPC-260F, manufactured by ULVAC KIKO, Inc.), and an aluminum
layer was formed over the electron injection layer by a vacuum
evaporation method so that a thickness of the aluminum film is 100 nm.
Thereby, a glass substrate K' over which a cathode was formed was
obtained.

[0349] The glass substrate K' over which the cathode was formed was sealed
under nitrogen atmosphere by using the sealing glass and the two-liquid
mixing-type epoxy resin (Robnor resins Ltd., trade name: PX681C/NC) to
prepare a light-emitting device k-7.

[0350] A forward direction voltage of 12 V was applied to the
light-emitting device k-7, and light-emitting brightness was measured.
The light-emitting brightness was 1,145 cd/m2. The light-emitting
device k-7 is a bottom emission type light-emitting device having a
forward stacked structure prepared by the coating method.

[0351] It is acknowledged that light transparency of the light-emitting
device of the present invention can improved because the light-emitting
device comprises electrodes having high conductivity and high
transparency even in the case of thin thickness of the electrode, and
characteristics such as light-emitting brightness of the light-emitting
device can be improved because the electron injection layer contains the
organic compound having at least one of the ionic group and the polar
group.

[0352] Similarly, it is acknowledged that light transparency of the
photovoltaic cell can be improved because the photovoltaic cell comprises
electrodes having high transparency, and characteristics such as
photovoltaic efficiency can be improved because the electron injection
layer contains the organic compound having at least one of the ionic
group and the polar group.

[0353] In addition, it is acknowledged that at least one of the cathode,
the anode, and the electron injection layer further contains an ionic
compound in addition to the organic compound having at least one of the
ionic group and the polar group, and thereby the electron injection
characteristic can be improved, and as a result, characteristics of the
light-emitting device and the photovoltaic cell can further be improved.

[0354] With method for manufacturing of the present invention, a formation
step of the cathode following the forming step of an electron injection
layer is formed by a convenient coating method that can be performed
under air atmosphere. Since these steps can be continuously performed,
the method for manufacturing can be more simplified, and the
light-emitting device and the photovoltaic cell having more excellent
characteristics can be manufactured in higher productivity.

[0355] As described above, the present invention provides extremely
significant contribution to the light-emitting device, the photovoltaic
cell, and the methods for manufacturing thereof.